Top 50 C Coding Interview Questions and Answers (2025)
Last Updated : 12 May, 2025
C is the most popular programming language developed by Dennis Ritchie at the Bell Laboratories in 1972 to develop the UNIX operating systems. It is a general-purpose and procedural programming language. It is faster than the languages like Java and Python. C is the most used language in top companies such as LinkedIn, Microsoft, Opera, Meta, and NASA because of its performance. To crack into these companies and other software companies, you need to master C.
This interview preparation guide on C Coding Interview Questions offers a comprehensive collection of practice questions suitable for both beginners and advanced learners.
List of 50 C Coding Interview Questions and Answers
Here is a list of 50 C coding interview questions and answers, to fully prepare for your next interview and ace those tough coding challenges, our C programming course offers a complete guide, including mock interview questions and detailed explanations.
1. Find the largest number among the three numbers.
C // C Program to find // Largest of three numbers #include <stdio.h> int main() { int a = 1, b = 2, c = 3; // condition for a is greatest if (a > b && a > c) printf("%d", a); // condition for b is greatest else if (b > a && b > c) printf("%d", b); // remaining conditions // c is greatest else printf("%d", c); return 0; } Refer to complete article - C program to Find the Largest Number Among Three Numbers
2. Write a Program to check whether a number is prime or not.
C // C Program for Checking value is // Prime or not #include <stdbool.h> #include <stdio.h> int main() { int n = 91; int cnt = 0; // If number is less than/equal to 1, // it is not prime if (n <= 1) printf("%d is NOT prime\n", n); else { // Check for divisors from 1 to n for (int i = 1; i <= n; i++) { // Check how many number is divisible // by n if (n % i == 0) cnt++; } // If n is divisible by more than 2 numbers // then it is not prime if (cnt > 2) printf("%d is NOT prime\n", n); // else it is prime else printf("%d is prime", n); } return 0; } Refer to complete article - Prime Number Program in C
3. Write a C program to calculate Compound Interest.
C // C program to calculate Compound Interest #include <stdio.h> // For using pow function we must // include math.h #include <math.h> // Driver code int main() { // Principal amount double principal = 2300; // Annual rate of interest double rate = 7; // Time double time = 4; // Calculating compound Interest double amount = principal * ((pow((1 + rate / 100), time))); double CI = amount - principal; printf("Compound Interest is : %lf", CI); return 0; } OutputCompound Interest is : 714.830823
Refer to complete article - C Program For Compound Interest
C // C Program to // Swap two numbers // No Extra Space #include <stdio.h> int main() { int x = 10; int y = 20; printf("x: %d , y: %d\n", x, y); // x hold 30 x = x + y; // y hold 10 y = x - y; // Now, x hold 20 x = x - y; printf("x: %d , y: %d\n", x, y); return 0; } Outputx: 10 , y: 20 x: 20 , y: 10
Refer to complete article - Swap Two Numbers Without Using Third Variable
5. Write a Program to Replace all 0’s with 1’s in a Number.
C // C Program for // Replacing 0 to 1 #include <math.h> #include <stdio.h> int main() { int N = 102301; int ans = 0; int i = 0; while (N != 0) { // Condition to change value if (N % 10 == 0) ans = ans + 1 * pow(10, i); else ans = ans + (N % 10) * pow(10, i); N = N / 10; i++; } printf("%d", ans); return 0; } Output:
112311
6. Write a Program to convert the binary number into a decimal number.
C // C Program for converting // binary to decimal #include <stdio.h> int main() { int N = 11011; // Initializing base value a to 1 int a = 1; int ans = 0; while (N != 0) { ans = ans + (N % 10) * a; N = N / 10; a = a * 2; } printf("%d", ans); return 0; } Refer to complete article - Convert Binary to Decimal in C
7. Write a Program to check if the year is a leap year or not.
C // C Program to check // Year is leap year or not #include <stdio.h> // Function Declaration to check leap year void leap_year(int year) { // If a year is multiple of 400, then leap year if (year % 400 == 0) printf("%d is a leap year.\n", year); // If a year is multiple of 100, then not a leap year else if (year % 100 == 0) printf("%d is not a leap year.\n", year); // If a year is multiple of 4, then leap year else if (year % 4 == 0) printf("%d is a leap year.\n", year); // Not leap year else printf("%d is not a leap year.\n", year); } int main() { leap_year(2000); leap_year(2002); leap_year(2008); return 0; } Output2000 is a leap year. 2002 is not a leap year. 2008 is a leap year.
Refer to complete article - Leap Year Program in C
8. Write a program to Factorial of a Number.
C // C Program to calculate // Factorial of a number #include <stdio.h> // Calculating factorial using iteration void factorial_iteration(int N) { unsigned long long int ans = 1; for (int i = 1; i <= N; i++) { ans = ans * i; } printf("Factorial of %d is %lld\n", N, ans); } // Calculating factorial using recursion int factorial(int N) { if (N == 0) return 1; // Recursive call return N * factorial(N - 1); } int main() { int n; n = 13; factorial_iteration(n); n = 9; printf("Factorial of %d using recursion:%d\n", n, factorial(n)); return 0; } OutputFactorial of 13 is 6227020800 Factorial of 9 using recursion:362880
Refer to complete article - Factorial Program in C
9. Write a Program to Check if a number is an Armstrong number or not.
C // C program to check if number // is Armstrong number or not #include <stdio.h> // Function to calculate x raised to the power y int power(int x, unsigned int y) { if (y == 0) return 1; if (y % 2 == 0) return power(x, y / 2) * power(x, y / 2); return x * power(x, y / 2) * power(x, y / 2); } // Function to calculate order of the number int order(int n) { int res = 0; while (n) { res++; n = n / 10; } return res; } // Function to check whether the given number is // Armstrong number or not int isArmstrong(int x) { // Calling order function int n = order(x); int temp = x, sum = 0; while (temp) { int r = temp % 10; sum += power(r, n); temp = temp / 10; } // If satisfies Armstrong condition if (sum == x) return 1; else return 0; } // Driver Program int main() { int x = 120; if (isArmstrong(x) == 1) printf("True\n"); else printf("False\n"); x = 1634; if (isArmstrong(x) == 1) printf("True\n"); else printf("False\n"); return 0; } Refer to complete article - C Program to Check Armstrong Number
10. Write a program to Find all the roots of a quadratic equation in C.
C // C program to find roots // of a quadratic equation #include <math.h> #include <stdio.h> #include <stdlib.h> // Prints roots of quadratic equation ax*2 + bx + x void find_roots(int a, int b, int c) { // If a is 0, then equation is not quadratic, but // linear if (a == 0) { printf("Invalid"); return; } int d = (b * b) - (4 * a * c); double sqrt_val = sqrt(abs(d)); if (d > 0) { printf("Roots are real and different \n"); printf("%f\n%f", (double)(-b + sqrt_val) / (2 * a), (double)(-b - sqrt_val) / (2 * a)); } else if (d == 0) { printf("Roots are real and same \n"); printf("%f", -(double)b / (2 * a)); } else // d < 0 { printf("Roots are complex \n"); printf("%f + i%f\n%f - i%f", -(double)b / (2 * a), sqrt_val / (2 * a), -(double)b / (2 * a), sqrt_val / (2 * a)); } } // Driver code int main() { int a = 1, b = -16, c = 1; // Function call find_roots(a, b, c); return 0; } Output:
Roots are real and different
15.937254
0.062746
Refer to complete article - C Program for Quadratic Equation Roots
11. Write a Program to reverse a number.
C // C Programs to Calculate // reverse of a number #include <stdio.h> // Iterative approach int reverse_iteration(int N) { int ans = 0; while (N != 0) { ans = ans * 10 + (N % 10); N = N / 10; } return ans; } // recursive approach int reverse(int n, int ans) { if (n == 0) return ans; ans = ans * 10 + n % 10; return reverse(n / 10, ans); } int main() { int N = 15942; printf("Initial number:%d\n", N); N = reverse_iteration(N); printf("%d after reverse using iteration\n", N); int ans = 0; ans = reverse(N, ans); printf("%d after again reverse using recursion", ans); return 0; } OutputInitial number:15942 24951 after reverse using iteration 15942 after again reverse using recursion
Refer to complete article - Reverse Number Program in C
12. Check whether a number is a palindrome.
C // C Program for // Checking Palindrome #include <stdio.h> // Checking if the number is // Palindrome number void check_palindrome(int N) { int T = N; int rev = 0; // This variable stored reversed digit // Execute a while loop to reverse digits of given // number while (T != 0) { rev = rev * 10 + T % 10; T = T / 10; } // Compare original_number with reversed number if (rev == N) printf("%d is palindrome\n", N); else printf("%d is not a palindrome\n", N); } int main() { int N = 13431; int M = 12345; // Function call check_palindrome(N); check_palindrome(M); return 0; } Output13431 is palindrome 12345 is not a palindrome
Refer to complete article - Palindrome Number Program in C
13. Write a C Program to check if two numbers are equal without using the comparison operator.
C // C Program for checking numbers // are equal using bitwise operator #include <stdio.h> int main() { int x = 1; int y = 2; // Using XOR // XOR of two equal numbers is 0 if (!(x ^ y)) printf(" %d is equal to %d ", x, y); else printf(" %d is not equal to %d ", x, y); return 0; } Output 1 is not equal to 2
14. Write a C program to find the GCD of two numbers.
C // C program to find GCD of two numbers #include <math.h> #include <stdio.h> // Function to return gcd of a and b int gcd(int a, int b) { // Find Minimum of a and b int result = ((a < b) ? a : b); while (result > 0) { if (a % result == 0 && b % result == 0) { break; } result--; } return result; // return gcd of a and b } // Driver program to test above function int main() { int a = 98, b = 56; printf("GCD of %d and %d is %d ", a, b, gcd(a, b)); return 0; } OutputGCD of 98 and 56 is 14
Refer to complete article - GCD of Two Numbers in C
15. Write a C program to find the LCM of two numbers.
C // C program to find // LCM of two numbers #include <stdio.h> // minimum of two numbers int Min(int Num1, int Num2) { if (Num1 >= Num2) return Num2; else return Num1; } int LCM(int Num1, int Num2, int K) { // If either of the two numbers // is 1, return their product if (Num1 == 1 || Num2 == 1) return Num1 * Num2; // If both the numbers are equal if (Num1 == Num2) return Num1; // If K is smaller than the // minimum of the two numbers if (K <= Min(Num1, Num2)) { // Checks if both numbers are // divisible by K or not if (Num1 % K == 0 && Num2 % K == 0) { // Recursively call LCM() function return K * LCM(Num1 / K, Num2 / K, 2); } // Otherwise else return LCM(Num1, Num2, K + 1); } // If K exceeds minimum else return Num1 * Num2; } int main() { // Given N & M int N = 12, M = 9; // Function Call int ans = LCM(N, M, 2); printf("%d", ans); return 0; } Refer to complete article - LCM of Two Numbers in C
16. Write a C Program to find the Maximum and minimum of two numbers without using any loop or condition.
C // C Program to check // Maximum and Minimum // Between two numbers // Without any condition or loop #include <stdio.h> #include <stdlib.h> int main() { int a = 55, b = 23; // return maximum among the two numbers printf("max = %d\n", ((a + b) + abs(a - b)) / 2); // return minimum among the two numbers printf("min = %d", ((a + b) - abs(a - b)) / 2); return 0; } 17. Write a Program in C to Print all natural numbers up to N without using a semi-colon.
C // C program to print // all natural numbers // upto N without using semi-colon #include <stdio.h> #define N 10 int main(int val) { if (val <= N && printf("%d ", val) && main(val + 1)) { } } Output1 2 3 4 5 6 7 8 9 10
Refer to complete article - C Program to print numbers from 1 to N without using semicolon?
18. Write a Program to find the area of a circle.
C // C program to find area // of circle #include <math.h> #include <stdio.h> #define PI 3.142 double findArea(int r) { return PI * pow(r, 2); } int main() { printf("Area is %f", findArea(5)); return 0; } Refer to complete article - C Program to Find Area of Circle
19. Write a Program to create a pyramid pattern using C.
C // C Program print Pyramid pattern #include <stdio.h> int main() { int N = 5; // Outer Loop for number of rows for (int i = 1; i <= N; i++) { // inner Loop for space printing for (int j = 1; j <= N - i; j++) printf(" "); // inner Loop for star printing for (int j = 1; j < 2 * i; j++) printf("*"); printf("\n"); } return 0; } Output * *** ***** ******* *********
Refer to complete article - C Program to Print Pyramid Pattern
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
C // C Program to print // Pascal's Triangle #include <stdio.h> int main() { int n = 5; for (int i = 1; i <= n; i++) { for (int j = 1; j <= n - i; j++) { printf(" "); } int x = 1; for (int j = 1; j <= i; j++) { printf("%d ", x); x = x * (i - j) / j; } printf("\n"); } return 0; } Output 1 1 1 1 2 1 1 3 3 1 1 4 6 4 1
Refer to complete article - Pascal Triangle Program in C
21. Write a Program to return the nth row of Pascal's triangle.
C // C program to return the Nth row of pascal's triangle #include <stdio.h> // Print the N-th row of the Pascal's Triangle void generateNthrow(int N) { // nC0 = 1 int prev = 1; printf("%d", prev); for (int i = 1; i <= N; i++) { // nCr = (nCr-1 * (n - r + 1))/r int curr = (prev * (N - i + 1)) / i; printf(",%d ", curr); prev = curr; } } int main() { int n = 5; generateNthrow(n); return 0; } 22. Write a program to reverse an Array.
C // C Program to reverse // An array #include <stdio.h> void reverse(int* arr, int n) { // Swapping front and back elements. for (int i = 0, j = n - 1; i < j; i++, j--) { int ele = arr[i]; arr[i] = arr[j]; arr[j] = ele; } } int main() { int arr[] = { 1, 2, 3, 4, 5 }; // Function Call reverse(arr, 5); // reverse array element printing for (int i = 0; i < 5; i++) printf("%d ", arr[i]); return 0; } Refer to complete article - Reverse Array in C
23. Write a program to check the repeating elements in C.
C // C Program for // checking duplicate // values in a array #include <stdio.h> int Sort(int arr[], int size) { for (int i = 0; i < size - 1; i++) { for (int j = 0; j < size - i - 1; j++) { if (arr[j] > arr[j + 1]) { int temp = arr[j]; arr[j] = arr[j + 1]; arr[j + 1] = temp; } } } } // find repeating element void findRepeating(int arr[], int n) { int count = 0; for (int i = 0; i < n; i++) { int flag = 0; while (i < n - 1 && arr[i] == arr[i + 1]) { flag = 1; i++; } if (flag) printf("%d ", (arr[i - 1])); } return; } int main() { int arr[] = { 1, 3, 4, 1, 2, 3, 5, 5 }; int n = sizeof(arr) / sizeof(arr[0]); Sort(arr,n); findRepeating(arr,n); return 0; } 24. Write a Program to print the Maximum and Minimum elements in an array.
C // C Program for calculating // maximum and minimum element #include <stdio.h> void find_small_large(int arr[], int n) { int min, max; // assign first element as minimum and maximum min = arr[0]; max = arr[0]; for (int i = 1; i < n; i++) { // finding smallest here if (arr[i] < min) min = arr[i]; // finding largest here if (arr[i] > max) max = arr[i]; } printf("Maximum: %d and Minimum: %d\n", min, max); } int main() { int arr[] = { 15, 14, 35, 2, 11, 83 }; int len = sizeof(arr) / sizeof(arr[0]); // Function call find_small_large(arr, len); return 0; } OutputSmallest: 2 and Largest: 83
Refer to complete article - C Program to Find the Maximum and Minimum Element in the Array
25. Write a Program for the cyclic rotation of an array to k positions.
C // C program to rotate // Array by k elements #include <stdio.h> // Print array void printArray(int arr[], int n) { int i; for (i = 0; i < n; i++) printf("%d ", arr[i]); } // Caculates greatest common divisor int gcd(int a, int b) { if (b == 0) return a; else return gcd(b, a % b); } // Rotate array void Rotate(int arr[], int k, int N) { int i, j, a, temp; k = k % N; int rotate = gcd(k, N); for (i = 0; i < rotate; i++) { temp = arr[i]; j = i; while (1) { a = j + k; if (a >= N) a = a - N; if (a == i) break; arr[j] = arr[a]; j = a; } arr[j] = temp; } } int main() { int arr[] = { 1, 2, 3, 4, 5 }; // Rotating array Rotate(arr, 2, 5); // Printing array printArray(arr, 5); return 0; } Refer to complete article - C Program for Program for array rotation
26. Write a Program to sort First half in Ascending order and the Second in Descending order.
C // C Program for Sorting // First half in Ascending order // and Second Descending order #include <stdio.h> void Sort_asc_desc(int arr[], int n) { int temp; for (int i = 0; i < n - 1; i++) { for (int j = i + 1; j < n; j++) { if (arr[i] > arr[j]) { temp = arr[i]; arr[i] = arr[j]; arr[j] = temp; } } } // printing first half in ascending order for (int i = 0; i < n / 2; i++) printf("%d ", arr[i]); // printing second half in descending order for (int j = n - 1; j >= n / 2; j--) printf("%d ", arr[j]); } int main() { int arr[] = { 11, 23, 42, 16, 83, 73, 59 }; int N = sizeof(arr) / sizeof(arr[0]); Sort_asc_desc(arr, N); return 0; } Output11 16 23 83 73 59 42
27. Write a Program to print sums of all subsets in an array.
C // C Program to print sum of // all subsets #include <stdio.h> // Function to print sum of subset // Using recursion void subset_sum(int arr[], int i, int j, int sum) { if (i > j) { printf("%d ", sum); return; } subset_sum(arr, i + 1, j, sum + arr[i]); subset_sum(arr, i + 1, j, sum); } // driver code int main() { int arr[] = { 1, 2, 3 }; int n = sizeof(arr) / sizeof(arr[0]); // Function calling to print subset sum subset_sum(arr, 0, n - 1, 0); return 0; } 28. Write a Program to Find if there is any subarray with a sum equal to 0.
C // C Program to check 0 sum // subarray possible #include <stdio.h> int main() { // array int arr[] = { -2, 2, 1, 1, 8 }; int n = sizeof(arr) / sizeof(arr[0]); int flag = 0, sum; // Traversing array to check for (int i = 0; i < n; i++) { for (int j = i; j < n; j++) { sum += arr[j]; if (sum == 0) { flag = 1; printf( "True subarray with 0 sum is possible"); break; } } } if (flag == 0) printf("No such condition"); } OutputTrue subarray with 0 sum is possible
29. Write a C program to Implement Kadane's Algorithm
C // C program to implement Kadane's Algorithm #include <limits.h> #include <stdio.h> int main() { int a[] = { -2, -3, 4, -1, -2, 1, 5, -3 }; int n = sizeof(a) / sizeof(a[0]); int max_so_far = INT_MIN, max_ending_here = 0, start = 0, end = 0, s = 0; for (int i = 0; i < n; i++) { max_ending_here += a[i]; if (max_so_far < max_ending_here) { max_so_far = max_ending_here; start = s; end = i; } if (max_ending_here < 0) { max_ending_here = 0; s = i + 1; } } printf("Maximum contiguous sum is %d\n", max_so_far); printf("Starting index %d Ending index %d", start, end); return 0; } OutputMaximum contiguous sum is 7 Starting index 2 Ending index 6
30. Write a Program to find the transpose of a matrix.
C #include <stdio.h> // This function stores transpose of A[][] in B[][] void transpose(int N, int M, int A[M][N], int B[N][M]) { int i, j; for (i = 0; i < N; i++) for (j = 0; j < M; j++) B[i][j] = A[j][i]; } int main() { int M = 3; int N = 4; int A[3][4] = { { 1, 1, 1, 1 }, { 2, 2, 2, 2 }, { 3, 3, 3, 3 } }; // Note dimensions of B[][] int B[N][M], i, j; transpose(N, M, A, B); printf("Result matrix is \n"); for (i = 0; i < N; i++) { for (j = 0; j < M; j++) printf("%d ", B[i][j]); printf("\n"); } return 0; } OutputResult matrix is 1 2 3 1 2 3 1 2 3 1 2 3
Refer to complete article - Transpose of a Matrix in C
31. Write a Program to Rotate a matrix by 90 degrees in the clockwise direction in C.
C // C Program to rotate the array // By 90 degree in clockwise direction #include <stdio.h> void swap(int* a, int* b){ int temp = *a; *a = *b; *b = temp; } int main() { int n = 4; int arr[4][4] = { { 1, 2, 3, 4 }, { 5, 6, 7, 8 }, { 9, 10, 11, 12 }, { 13, 14, 15, 16 } }; // Print Orignal Matrix printf("Orignal Matrix:\n"); for (int i = 0; i < n; i++) { for (int j = 0; j < n; j++) { printf("%d ", arr[i][j]); } printf("\n"); } // Rotate the matrix about the main diagonal for (int i = 0; i < n; i++) { for (int j = 0; j < i; j++) swap(&arr[i][j], &arr[j][i]); } // Rotate the matrix about middle column for (int i = 0; i < n; i++) { for (int j = 0; j < n / 2; j++) { swap(&arr[i][j], &arr[i][n - j - 1]); } } // Print the rotated matrix printf("Matrix after rotation: \n"); for (int i = 0; i < n; i++) { for (int j = 0; j < n; j++) { printf("%d ", arr[i][j]); } printf("\n"); } } OutputOrignal Matrix: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Matrix after rotation: 13 9 5 1 14 10 6 2 15 11 7 3 16 12 8 4
Refer to complete article - Rotate an Image 90 Degree Clockwise
32. Write a Program to find the Spiral Traversal of a Matrix in C.
C // C Program to find Spiral Traversal // Of a matrix #include <stdio.h> int main() { int arr[4][4] = { { 1, 5, 9, 13 }, { 2, 6, 10, 14 }, { 3, 7, 11, 15 }, { 4, 8, 12, 16 } }; int m = 4, n = 4; int i, l = 0, right = m - 1, begin = 0, end = n - 1; while (l <= right && begin <= end) { // Print the first row // from the remaining rows for (i = l; i <= right; ++i) { printf("%d ", arr[begin][i]); } begin++; // Print the last column // from the remaining columns for (i = begin; i <= end; ++i) { printf("%d ", arr[i][right]); } right--; // Print the last row from // the remaining rows if (begin <= end) { for (i = right; i >= l; --i) { printf("%d ", arr[end][i]); } end--; } // Print the first column from // the remaining columns if (l <= right) { for (i = end; i >= begin; --i) { printf("%d ", arr[i][l]); } l++; } } return 0; } Output1 5 9 13 14 15 16 12 8 4 3 2 6 10 11 7
33. Write a program to count the sum of numbers in a string.
C #include <stdio.h> int main() { char s[] = "124259"; int ans = 0; // iterate through all the number for (int i = 0; s[i] != '\0'; i++) { int ele = s[i] - 48; if (ele <= 9) ans += ele; } // print sum of the numbers printf("%d", ans); return 0; } 34. Program to calculate the length of the string.
C // C Program to calculate // length of a string #include <stdio.h> #include <string.h> int length(char s[], int i) { if (s[i] == '\0') return 0; return length(s, i + 1) + 1; } int main() { char s[] = "GeeksforGeeks"; // Calculating using strlen int len = strlen(s); printf("length using strlen:%d\n", len); // Calculating using iteration int i; for (i = 0; s[i] != '\0'; i++) { continue; } printf("length using iteration:%d\n", i); // Calculating using recursion int ans = length(s, 0); printf("length using recursion:%d\n", ans); return 0; } Outputlength using strlen:13 length using iteration:13 length using recursion:13
Refer to complete article - C Program to Find the Length of a String
35. Write a program to check string is a palindrome.
C // C implementation to check if a given // string is palindrome or not #include <stdio.h> #include <string.h> #include <stdbool.h> bool is_palindrome(char* str, int i, int j) { if (i >= j) { return true; } if (str[i] != str[j]) { return false; } return is_palindrome(str, i + 1, j - 1); } void check_palindrome(char* str) { // Start from leftmost and // rightmost corners of str int h = 0; int flag = 0; int l = strlen(str) - 1; // Keep comparing characters // while they are same while (h > l) { if (str[l++] != str[h--]) { printf("%s is not a palindrome\n", str); flag = 1; break; // will break from here } } if (flag == 0) printf("%s is a palindrome\n", str); } int main() { char str[] = { "GeekeeG" }; char str2[] = { "GeeksforGeeks" }; check_palindrome(str); printf("Checking %s using recursive approach\n", str2); bool ans = is_palindrome(str2,0,strlen(str2)-1); if (ans) printf("It is Palindrome\n"); else printf("Not a Palindrome\n"); return 0; } OutputGeekeeG is a palindrome Checking GeeksforGeeks using recursive approach Not a Palindrome
Refer to complete article - C Program to Check for Palindrome String
36. Write a program to print all permutations of a given string in lexicographically sorted order in C.
C // C Program to print all permutations of a string in sorted // order. #include <stdio.h> #include <stdlib.h> #include <string.h> // function two compare two characters a and b int compare(const void* a, const void* b) { return (*(char*)a - *(char*)b); } // function two swap two characters a and b void swap(char* a, char* b) { char t = *a; *a = *b; *b = t; } // function finds the index of the smallest character int findCeil(char str[], char first, int l, int h) { int ceilIndex = l; for (int i = l + 1; i <= h; i++) if (str[i] > first && str[i] < str[ceilIndex]) ceilIndex = i; return ceilIndex; } // Print all permutations of str in sorted order void sortedPermutations(char str[]) { int size = strlen(str); qsort(str, size, sizeof(str[0]), compare); int isFinished = 0; while (!isFinished) { printf("%s \n", str); int i; for (i = size - 2; i >= 0; --i) if (str[i] < str[i + 1]) break; if (i == -1) isFinished = 1; else { int ceilIndex = findCeil(str, str[i], i + 1, size - 1); swap(&str[i], &str[ceilIndex]); qsort(str + i + 1, size - i - 1, sizeof(str[0]), compare); } } } int main() { char str[] = "123"; sortedPermutations(str); return 0; } Output123 132 213 231 312 321
37. Write a program to calculate the Power of a Number using Recursion in C.
C // C program to calculate the Power of a Number using // Recursion #include <stdio.h> int power(int a, int b) { if (b == 0) return 1; return power(a, b - 1) * a; } int main() { int a = 4, b = 5; int ans = power(a, b); printf("%d", ans); return 0; } 38. Write a Code to print the Fibonacci series using recursion.
C // C Program to illustrate // Fibonacci Series using Recursion #include <stdio.h> int fibonacci(int n) { if (n <= 1) return n; return fibonacci(n - 1) + fibonacci(n - 2); } int fibonacci_iteration(int n) { if (n <= 1) return 1; int arr[n + 1]; arr[0] = 1; arr[1] = 1; for (int i = 2; i < n + 1; i++) arr[i] = arr[i - 1] + arr[i - 2]; return arr[n]; } int main() { int n = 9; printf("Fibonacci using recursion of %d:%d\n", n, fibonacci(n)); n = 11; printf("Fibonacci using iteration of %d:%d", n, fibonacci_iteration(n)); return 0; } OutputFibonacci using recursion of 9:34 Fibonacci using iteration of 11:144
Refer to complete article - C Program to Print Fibonacci Series
39. Write a Program to find the HCF of two Numbers using Recursion.
C // C program to find // GCD of two numbers #include <stdio.h> // Recursive function to // Calculate and return gcd of a and b int gcd(int a, int b) { // Everything divides 0 if (a == 0) return b; if (b == 0) return a; // base case if (a == b) return a; // a is greater if (a > b) return gcd(a - b, b); return gcd(a, b - a); } int main() { int a = 192, b = 36; printf("GCD of %d and %d is %d ", a, b, gcd(a, b)); return 0; } OutputGCD of 192 and 36 is 12
40. Write a Program in C to reverse a string using recursion.
C // C program to reverse // String using recursion #include <stdio.h> #include <string.h> // Using Iteration for reverse void reverse_iteration(char* str) { int i = 0; int j = strlen(str) - 1; for (; i < j; i++, j--) { char temp = str[i]; str[i] = str[j]; str[j] = temp; } } // Using recursion for reverse void reverse(char* str) { if (*str) { reverse(str + 1); printf("%c", *str); } } int main() { char a[] = "Geeks for Geeks"; printf("Orignal string:%s\n", a); reverse_iteration(a); printf("Reverse the string(iteration):%s\n", a); printf("Using recursion for reverse:"); reverse(a); return 0; } OutputOrignal string:Geeks for Geeks Reverse the string(iteration):skeeG rof skeeG Using recursion for reverse:Geeks for Geeks
Refer to complete article - C Program to Reverse a String Using Recursion
C Coding Interview Questions and Answers41. Write a C Program to search elements in an array.
C // C code to Search elements in array #include <stdio.h> int search(int arr[], int N, int x) { int i; // iterate through all the element of array for (i = 0; i < N; i++) if (arr[i] == x) return i; return -1; } int main(void) { int arr[] = { 9, 3, 2, 1, 10, 4 }; int x = 10; int N = sizeof(arr) / sizeof(arr[0]); // Function Call int result = search(arr, N, x); if (result == -1) { printf("Element is not present in array"); } else { printf("Element is present at index %d", result); } return 0; } OutputElement is present at index 4
Refer to complete article - C Program for Linear Search
42. Write a C Program to search elements in an array using Binary Search.
C // C program to Search element // in Array using Binary Search #include <stdio.h> int binarySearch(int arr[], int l, int r, int x) { if (r >= l) { int mid = l + (r - l) / 2; // If the element is present at the middle // itself if (arr[mid] == x) return mid; // If element is smaller than mid, then // it can only be present in left subarray if (arr[mid] > x) return binarySearch(arr, l, mid - 1, x); // Else the element can only be present // in right subarray return binarySearch(arr, mid + 1, r, x); } return -1; } int main() { int arr[] = { 11, 14, 19, 23, 40 }; int n = sizeof(arr) / sizeof(arr[0]); int x = 40; int result = binarySearch(arr, 0, n - 1, x); if (result == -1) { printf("Element is not present in array"); } else { printf("Element is present at index %d", result); } return 0; } OutputElement is present at index 4
Refer to complete article - C Program for Binary Search | GeeksforGeeks
43. Write a C Program to sort arrays using Bubble, Selection, and Insertion Sort.
C // C Program to implement // Sorting Algorithms #include <stdio.h> // A function to implement bubble sort void bubble_sort(int* arr, int n) { for (int j = 0; j < n - 1; j++) { // Last j elements are already in place for (int i = 0; i < n - j - 1; i++) { if (arr[i] > arr[i + 1]) { int temp = arr[i]; arr[i] = arr[i + 1]; arr[i + 1] = temp; } } } } // A function to implement swaping void swap(int* xp, int* yp) { int temp = *xp; *xp = *yp; *yp = temp; } // A function to implement selectionSort void selectionSort(int arr[], int n) { // One by one move boundary of unsorted subarray for (int i = 0; i < n - 1; i++) { // Find the minimum element in unsorted array int min_idx = i; for (int j = i + 1; j < n; j++) if (arr[j] < arr[min_idx]) min_idx = j; // Swap the found minimum element // with the first element if (min_idx != i) swap(&arr[min_idx], &arr[i]); } } void insertionSort(int arr[], int n) { for (int i = 1; i < n; i++) { int key = arr[i]; int j = i - 1; // Move elements of arr that are // greater than key, to one position ahead // of their current position while (j >= 0 && arr[j] > key) { arr[j + 1] = arr[j]; j = j - 1; } arr[j + 1] = key; } } int main() { int arr1[] = { 9, 4, 3, 11, 1, 5 }; int arr2[] = { 4, 3, 9, 1, 5, 11 }; int arr3[] = { 5, 1, 11, 3, 4, 9 }; int n = 6; printf("Non-Sorted array: "); for (int i = 0; i < n; i++) printf("%d ", arr1[i]); printf("\n"); // sort array bubble_sort(arr1, n); // printing array printf("Sorted array using Bubble sort: "); for (int i = 0; i < n; i++) printf("%d ", arr1[i]); printf("\n"); printf("Non-Sorted array: "); for (int i = 0; i < n; i++) printf("%d ", arr2[i]); printf("\n"); // sort array insertionSort(arr2, n); // printing array printf("Sorted array using Insertion Sort: "); for (int i = 0; i < n; i++) printf("%d ", arr2[i]); printf("\n"); printf("Non-Sorted array: "); for (int i = 0; i < n; i++) printf("%d ", arr3[i]); printf("\n"); // sort array selectionSort(arr3, n); // printing array printf("Sorted array using Selection Sort: "); for (int i = 0; i < n; i++) printf("%d ", arr3[i]); printf("\n"); return 0; } OutputNon-Sorted array: 9 4 3 11 1 5 Sorted array using Bubble sort: 1 3 4 5 9 11 Non-Sorted array: 4 3 9 1 5 11 Sorted array using Insertion Sort: 1 3 4 5 9 11 Non-Sorted array: 5 1 11 3 4 9 Sorted array using Selection Sort: 1 3 4 5 9 11
44. Write a C Program to sort arrays using Merge Sort.
C // C program for // Sorting array // using Merge Sort #include <stdio.h> void merge(int arr[], int l, int m, int r) { int i, j, k; int n1 = m - l + 1; int n2 = r - m; // create temperary arrays int L[n1], R[n2]; // Copy data to arrays from L[] and R[] for (i = 0; i < n1; i++) L[i] = arr[l + i]; for (j = 0; j < n2; j++) R[j] = arr[m + 1 + j]; // Initial index of first ,second // and merged subarray respectively i = 0; j = 0; k = l; while (i < n1 && j < n2) { if (L[i] <= R[j]) { arr[k] = L[i]; i++; } else { arr[k] = R[j]; j++; } k++; } // Copy the remaining elements of L[] while (i < n1) { arr[k] = L[i]; i++; k++; } // Copy the remaining elements of R[] while (j < n2) { arr[k] = R[j]; j++; k++; } } void mergeSort(int arr[], int l, int r) { if (l < r) { // calculating middle term int mid = l + (r - l) / 2; // divide to sort both halves mergeSort(arr, l, mid); mergeSort(arr, mid + 1, r); merge(arr, l, mid, r); } } int main() { int arr[] = { 23, 9, 13, 15, 6, 7 }; int n = sizeof(arr) / sizeof(arr[0]); // Printing orignal array printf("Given array:"); for (int i = 0; i < n; i++) printf("%d ", arr[i]); printf("\n"); mergeSort(arr, 0, n - 1); // Printing sorted array printf("Sorted array :"); for (int i = 0; i < n; i++) printf("%d ", arr[i]); printf("\n"); return 0; } OutputGiven array:23 9 13 15 6 7 Sorted array :6 7 9 13 15 23
Refer to complete article - C Program for Merge Sort
45. Write a C Program to sort arrays using Quick Sort.
C // C Program for // sorting array using // Quick sort #include <stdio.h> void swap(int* a, int* b) { int t = *a; *a = *b; *b = t; } int partition(int array[], int low, int high) { int pivot = array[high]; int i = (low - 1); // compare elements with the pivot for (int j = low; j < high; j++) { if (array[j] <= pivot) { i++; swap(&array[i], &array[j]); } } // swap the pivot element with the greater element at i swap(&array[i + 1], &array[high]); return (i + 1); } void quickSort(int array[], int low, int high) { if (low < high) { int pi = partition(array, low, high); quickSort(array, low, pi - 1); quickSort(array, pi + 1, high); } } void printArray(int array[], int n) { for (int i = 0; i < n; ++i) { printf("%d ", array[i]); } printf("\n"); } int main() { int arr[] = { 28, 7, 20, 1, 10, 3 , 6 }; int n = sizeof(arr) / sizeof(arr[0]); printf("Unsorted Array:"); printArray(arr, n); quickSort(arr, 0, n - 1); printf("Sorted array :"); printArray(arr, n); return 0; } OutputUnsorted Array:28 7 20 1 10 3 6 Sorted array :1 3 6 7 10 20 28
Refer to complete article - Quick Sort in C
46. Write a program to sort an array using pointers.
C // C Program to implement // sorting using pointers #include <stdio.h> // Function to sort the numbers using pointers void sort(int n, int* ptr) { int i, j; // Sort the numbers using pointers for (i = 0; i < n; i++) { for (j = i + 1; j < n; j++) { if (*(ptr + j) < *(ptr + i)) { int temp = *(ptr + i); *(ptr + i) = *(ptr + j); *(ptr + j) = temp; } } } // print the numbers for (i = 0; i < n; i++) printf("%d ", *(ptr + i)); } // Driver code int main() { int n = 5; int arr[] = { 13, 22, 7, 12, 4 }; sort(n, arr); return 0; } Refer to complete article - C program to sort an array using pointers
C // C Program to Store // Information about Students // Using Structure #include <stdio.h> #include <stdlib.h> #include <string.h> // Create the student structure struct Student { char* name; int roll_number; int age; }; // Driver code int main() { int n = 3; // Create the student's structure variable // with n Student's records struct Student student[n]; // Get the students data student[0].roll_number = 1; student[0].name = "Geeks1"; student[0].age = 10; student[1].roll_number = 2; student[1].name = "Geeks2"; student[1].age = 11; student[2].roll_number = 3; student[2].name = "Geeks3"; student[2].age = 13; // Printing the Structers printf("Student Records:\n\n"); for (int i = 0; i < n; i++) { printf("\tName : %s", student[i].name); printf("\tRoll Number : %d", student[i].roll_number); printf("\tAge : %d\n", student[i].age); } return 0; } OutputStudent Records: Name : Geeks1 Roll Number : 1 Age : 10 Name : Geeks2 Roll Number : 2 Age : 11 Name : Geeks3 Roll Number : 3 Age : 13
Refer to complete article - C Program to Store Information of Students Using Structure
48. Write a C Program To Add Two Complex Numbers Using Structures And Functions.
C // C program to demonstrate // addition of complex numbers #include <stdio.h> // define a structure for complex number typedef struct complexNumber { int real; int img; } complex; complex add(complex x, complex y) { // define a new complex number. complex add; // add similar type together add.real = x.real + y.real; add.img = x.img + y.img; return (add); } int main() { // define three complex type numbers complex x, y, sum; // first complex number x.real = 4; x.img = 5; // second complex number y.real = 7; y.img = 11; // printing both complex numbers printf(" x = %d + %di\n", x.real, x.img); printf(" y = %d + %di\n", y.real, y.img); // call add(a,b) function and // pass complex numbers a & b // as an parameter. sum = add(x, y); // print result printf("\n sum = %d + %di", sum.real, sum.img); return 0; } Output x = 4 + 5i y = 7 + 11i sum = 11 + 16i
C // C program for calculating sum of // Distance in intches and feet #include "stdio.h" // Struct defined for the inch-feet system struct InchFeet { int feet; float inch; }; // Function to find the sum of all N // set of Inch Feet distances void findSum(struct InchFeet arr[], int N) { // Variable to store sum int feet_sum = 0; float inch_sum = 0.0; int x; // Traverse the InchFeet array for (int i = 0; i < N; i++) { // Find the total sum of // feet and inch feet_sum += arr[i].feet; inch_sum += arr[i].inch; } // If inch sum is greater than 11 // convert it into feet // as 1 feet = 12 inch if (inch_sum >= 12) { // Find integral part of inch_sum x = (int)inch_sum; // Delete the integral part x inch_sum -= x; // Add x%12 to inch_sum inch_sum += x % 12; // Add x/12 to feet_sum feet_sum += x / 12; } // Print the corresponding sum of // feet_sum and inch_sum printf("Feet Sum: %d\n", feet_sum); printf("Inch Sum: %.2f", inch_sum); } int main() { struct InchFeet arr[] = { { 11, 5.1 }, { 13, 4.5 }, { 6, 8.1 } }; int N = sizeof(arr) / sizeof(arr[0]); findSum(arr, N); return 0; } OutputFeet Sum: 31 Inch Sum: 5.70
Refer to complete article - C Program to Add N Distances Given in inch-feet System using Structures
50. Write a C program to reverse a linked list iteratively
C // C program to reverse a linked list iteratively #include <stdio.h> #include <stdlib.h> /* Link list node */ struct Node { int data; struct Node* next; }; /* Function to reverse the linked list */ static void reverse(struct Node** head_ref) { struct Node* prev = NULL; struct Node* current = *head_ref; struct Node* next = NULL; while (current != NULL) { // Store next next = current->next; // Reverse current node's pointer current->next = prev; // Move pointers one position ahead. prev = current; current = next; } *head_ref = prev; } /* Function to push a node */ void push(struct Node** head_ref, int new_data) { struct Node* new_node = (struct Node*)malloc(sizeof(struct Node)); new_node->data = new_data; new_node->next = (*head_ref); (*head_ref) = new_node; } /* Function to print linked list */ void printList(struct Node* head) { struct Node* temp = head; while (temp != NULL) { printf("%d ", temp->data); temp = temp->next; } } /* Driver code*/ int main() { /* Start with the empty list */ struct Node* head = NULL; push(&head, 10); push(&head, 14); push(&head, 19); push(&head, 25); printf("Given linked list\n"); printList(head); reverse(&head); printf("\nReversed linked list \n"); printList(head); getchar(); } OutputGiven linked list 25 19 14 10 Reversed linked list 10 14 19 25
Refer to complete article - C Program for Reverse a linked list
Conclusion
In this C coding interview questions and answers, we've compiled a wide-range of practice questions suitable for individuals at all levels, from beginners to advanced learners. Exploring these questions and their solutions will not only enhance your proficiency in C but also prepare you for a successful coding interview experience.
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C Control Statements Decision-Making
Decision Making in C (if , if..else, Nested if, if-else-if )In C, programs can choose which part of the code to execute based on some condition. This ability is called decision making and the statements used for it are called conditional statements. These statements evaluate one or more conditions and make the decision whether to execute a block of code or n
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C - if StatementThe if in C is the simplest decision-making statement. It consists of the test condition and a block of code that is executed if and only if the given condition is true. Otherwise, it is skipped from execution.Let's take a look at an example:C#include <stdio.h> int main() { int n = 9; // if st
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C if else StatementThe if else in C is an extension of the if statement which not only allows the program to execute one block of code if a condition is true, but also a different block if the condition is false. This enables making decisions with two possible outcomes.Example:C#include <stdio.h> int main() { in
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C if , else if ladderIn C, if else if ladder is an extension of if else statement used to test a series of conditions sequentially, executing the code for the first true condition. A condition is checked only if all previous ones are false. Once a condition is true, its code block executes, and the ladder ends.Example:C
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Switch Statement in CC switch statement is a conditional statement that allows you to execute different code blocks based on the value of a variable or an expression. It is often used in place of if-else ladder when there are multiple conditions.Example:C#include <stdio.h> int main() { // Switch variable int var =
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Using Range in switch Case in CYou all are familiar with switch case in C, but did you know you can use a range of numbers instead of a single number or character in the case statement? Range in switch case can be useful when we want to run the same set of statements for a range of numbers so that we do not have to write cases se
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C - LoopsIn C programming, there is often a need for repeating the same part of the code multiple times. For example, to print a text three times, we have to use printf() three times as shown in the code:C#include <stdio.h> int main() { printf( "Hello GfG\n"); printf( "Hello GfG\n"); printf( "Hello GfG
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C for LoopIn C programming, the 'for' loop is a control flow statement that is used to repeatedly execute a block of code as many times as instructed. It uses a variable (loop variable) whose value is used to decide the number of repetitions. It is commonly used to iterate over a sequence such as an array or
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while Loop in CThe while loop in C allows a block of code to be executed repeatedly as long as a given condition remains true. It is often used when we want to repeat a block of code till some condition is satisfied.Example: C#include <stdio.h> int main() { int i = 1; // Condition for the loop while (i <=
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do...while Loop in CC do...while loop is a type of loop that executes a code block until the given condition is satisfied. Unlike the while loop, which checks the condition before executing the loop, the do...while loop checks the condition after executing the code block, ensuring that the code inside the loop is execu
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For vs. WhileIn C, loops are the fundamental part of language that are used to repeat a block of code multiple times. The two most commonly used loops are the for loop and the while loop. Although they achieve the same result, their structure, use cases, and flexibility differ.The below table highlights some pri
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Continue Statement in CThe continue statement in C is a jump statement used to skip the current iteration of a loop and continue with the next iteration. It is used inside loops (for, while, or do-while) along with the conditional statements to bypass the remaining statements in the current iteration and move on to the ne
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Break Statement in CThe break statement in C is a loop control statement that breaks out of the loop when encountered. It can be used inside loops or switch statements to bring the control out of the block. The break statement can only break out of a single loop at a time.Example:C#include <stdio.h> int main() {
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goto Statement in CThe goto statement in C allows the program to jump to some part of the code, giving you more control over its execution. While it can be useful in certain situations, like error handling or exiting complex loops, it's generally not recommended because it can make the code harder to read and maintain
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C Functions
C FunctionsA function in C is a set of statements that, when called, perform some specific tasks. It is the basic building block of a C program that provides modularity and code reusability. They are also called subroutines or procedures in other languages.Function DefinitionA function definition informs the c
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User-Defined Function in CA user-defined function is a type of function in C language that is defined by the user himself to perform some specific task. It provides code reusability and modularity to our program. User-defined functions are different from built-in functions as their working is specified by the user and no hea
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Parameter Passing Techniques in CIn C, passing values to a function means providing data to the function when it is called so that the function can use or manipulate that data. Here:Formal Parameters: Variables used in parameter list in a function declaration/definition as placeholders. Also called only parameters.Actual Parameters
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Function Prototype in CIn C, a function prototype is a statement that tells the compiler about the function’s name, its return type, numbers, and data types of its parameters. Using this information, the compiler cross-checks function parameters and their data type with function definition and function call.For example, l
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How can I return multiple values from a function?In C programming, a function can return only one value directly. However, C also provides several indirect methods in to return multiple values from a function. In this article, we will learn the different ways to return multiple values from a function in C.The most straightforward method to return
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main Function in CThe main function is the entry point of a C program. It is a user-defined function where the execution of a program starts. Every C program must contain, and its return value typically indicates the success or failure of the program. In this article, we will learn more about the main function in C.E
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Implicit Return Type int in CIn C, every function has a return type that indicates the type of value it will return, and it is defined at the time of function declaration or definition. But in C language, it is possible to define functions without mentioning the return type and by default, int is implicitly assumed that the ret
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Callbacks in CIn C language, a callback is a function that is passed as an argument to another code, which is expected to call back (execute) the argument at a given time. In simple terms, a callback is the process of passing a function (executable code) to another function as an argument, which is then called by
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Nested Functions in CNesting of functions refers to placing the definition of the function inside another functions. In C programming, nested functions are not allowed. We can only define a function globally.Example:C#include <stdio.h> int main() { void fun(){ printf("GeeksForGeeks"); } fun(); return 0; }Outputmai
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Variadic Functions in CIn C, variadic functions are functions that can take a variable number of arguments. This feature is useful when the number of arguments for a function is unknown. It takes one fixed argument and then any number of arguments can be passed.Let's take a look at an example:C#include <stdio.h> #in
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_Noreturn function specifier in CIn C, the _Noreturn specifier is used to indicate that a function does not return a value. It tells the compiler that the function will either exit the program or enter an infinite loop, so it will never return control to the calling function. This helps the compiler to optimize code and issue warni
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Predefined Identifier __func__ in CBefore we start discussing __func__, let us write some code snippets and anticipate the output: C // C program to demonstrate working of a // Predefined Identifier __func__ #include <stdio.h> int main() { // %s indicates that the program will read strings printf("%s", __func__); return 0; } Ou
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C Library math.h FunctionsThe math.h header defines various C mathematical functions and one macro. All the functions available in this library take double as an argument and return double as the result. Let us discuss some important C math functions one by one. C Math Functions1. double ceil (double x) The C library functio
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C Arrays & Strings
C ArraysAn array in C is a fixed-size collection of similar data items stored in contiguous memory locations. It can be used to store the collection of primitive data types such as int, char, float, etc., as well as derived and user-defined data types such as pointers, structures, etc. Creating an Array in
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Properties of Array in CAn array in C is a fixed-size homogeneous collection of elements stored at a contiguous memory location. It is a derived data type in C that can store elements of different data types such as int, char, struct, etc. It is one of the most popular data types widely used by programmers to solve differe
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Multidimensional Arrays in C - 2D and 3D ArraysA multi-dimensional array in C can be defined as an array that has more than one dimension. Having more than one dimension means that it can grow in multiple directions. Some popular multidimensional arrays include 2D arrays which grows in two dimensions, and 3D arrays which grows in three dimension
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Initialization of Multidimensional Array in CIn C, multidimensional arrays are the arrays that contain more than one dimensions. These arrays are useful when we need to store data in a table or matrix-like structure. In this article, we will learn the different methods to initialize a multidimensional array in C. The easiest method for initial
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Pass Array to Functions in CPassing an array to a function allows the function to directly access and modify the original array. In this article, we will learn how to pass arrays to functions in C.In C, arrays are always passed to function as pointers. They cannot be passed by value because of the array decay due to which, whe
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How to pass a 2D array as a parameter in C?A 2D array is essentially an array of arrays, where each element of the main array holds another array. In this article, we will see how to pass a 2D array to a function.The simplest and most common method to pass 2D array to a function is by specifying the parameter as 2D array with row size and co
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What are the data types for which it is not possible to create an array?In C, an array is a collection of variables of the same data type, stored in contiguous memory locations. Arrays can store data of primitive types like integers, characters, and floats, as well as user-defined types like structures.However, there are certain data types for which arrays cannot be dir
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How to pass an array by value in C ?In C programming, arrays are always passed as pointers to the function. There are no direct ways to pass the array by value. However, there is trick that allows you to simulate the passing of array by value by enclosing it inside a structure and then passing that structure by value. This will also p
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Strings in CA String in C programming is a sequence of characters terminated with a null character '\0'. The C String is work as an array of characters. The difference between a character array and a C string is that the string in C is terminated with a unique character '\0'.DeclarationDeclaring a string in C i
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Array of Strings in CIn C, an array of strings is a 2D array where each row contains a sequence of characters terminated by a '\0' NULL character (strings). It is used to store multiple strings in a single array.Let's take a look at an example:C#include <stdio.h> int main() { // Creating array of strings for 3 str
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What is the difference between single quoted and double quoted declaration of char array?In C programming, the way we declare and initialize a char array can differ based on whether we want to use a sequence of characters and strings. They are basically same with difference only of a '\0' NULL character.Double quotes automatically include the null terminator, making the array a string l
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C String FunctionsC language provides various built-in functions that can be used for various operations and manipulations on strings. These string functions make it easier to perform tasks such as string copy, concatenation, comparison, length, etc. The <string.h> header file contains these string functions.Th
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C Pointers
C PointersA pointer is a variable that stores the memory address of another variable. Instead of holding a direct value, it has the address where the value is stored in memory. This allows us to manipulate the data stored at a specific memory location without actually using its variable. It is the backbone of
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Pointer Arithmetics in C with ExamplesPointer Arithmetic is the set of valid arithmetic operations that can be performed on pointers. The pointer variables store the memory address of another variable. It doesn't store any value. Hence, there are only a few operations that are allowed to perform on Pointers in C language. The C pointer
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C - Pointer to Pointer (Double Pointer)In C, double pointers are those pointers which stores the address of another pointer. The first pointer is used to store the address of the variable, and the second pointer is used to store the address of the first pointer. That is why they are also known as a pointer to pointer.Let's take a look at
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Function Pointer in CIn C, a function pointer is a type of pointer that stores the address of a function, allowing functions to be passed as arguments and invoked dynamically. It is useful in techniques such as callback functions, event-driven programs, and polymorphism (a concept where a function or operator behaves di
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How to Declare a Pointer to a Function?A pointer to a function is similar to a pointer to a variable. However, instead of pointing to a variable, it points to the address of a function. This allows the function to be called indirectly, which is useful in situations like callback functions or event-driven programming.In this article, we w
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Pointer to an Array | Array PointerA pointer to an array is a pointer that points to the whole array instead of the first element of the array. It considers the whole array as a single unit instead of it being a collection of given elements.Example:C #include<stdio.h> int main() { int arr[5] = { 1, 2, 3, 4, 5 }; int *ptr = arr;
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Difference between constant pointer, pointers to constant, and constant pointers to constantsIn this article, we will discuss the differences between constant pointer, pointers to constant & constant pointers to constants. Pointers are the variables that hold the address of some other variables, constants, or functions. There are several ways to qualify pointers using const. Pointers to
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Pointer vs Array in CMost of the time, pointer and array accesses can be treated as acting the same, the major exceptions being:  1. the sizeof operator sizeof(array) returns the amount of memory used by all elements in the array sizeof(pointer) only returns the amount of memory used by the pointer variable itself 2.
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Dangling, Void , Null and Wild Pointers in CIn C programming pointers are used to manipulate memory addresses, to store the address of some variable or memory location. But certain situations and characteristics related to pointers become challenging in terms of memory safety and program behavior these include Dangling (when pointing to deall
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Near, Far and Huge Pointers in CIn older times, the intel processors had 16-bit registers, but the address bus was 20-bits wide. Due to this, CPU registers were not able to hold the entire address at once. As a solution, the memory was divided into segments of 64 kB size, and the near pointers, far pointers, and huge pointers were
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restrict Keyword in CThe restrict keyword is a type qualifier that was introduced in the C99 standard. It is used to tell the compiler that a pointer is the only reference or access point to the memory it points to, allowing the compiler to make optimizations based on that information.Let's take a look at an example:C#i
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