Range-Based for Loop in C++

Last Updated : 19 Mar, 2025

In C++, the range-based for loop introduced in C++ 11 is a version of for loop that is able to iterate over a range. This range can be anything that is iteratable, such as arrays, strings and STL containers. It provides a more readable and concise syntax compared to traditional for loops.

Let’s take a look at an example:

C++

#include <bits/stdc++.h> using namespace std;  int main() {     vector<int> v = {1, 2, 3, 4, 5};      // Iterating through vector     for (int i : v) {         cout << i << " ";     }        return 0; }

Output

1 2 3 4 5

Explanation: In this program, the vector is iterated using range based for loop. As we can see, we don’t need to pass any size information or any iterator to iterate the vector. We just use the name of the vector.

Syntax of Range Based for Loop

for (declaration: range) {
// statements
}

where,

declaration: Declaration of the variable that will be used to represent each element of the range.
range: Name of the range.

The range-based for loop simplifies iteration over containers in C++.

Examples of Range Based for Loop

The below example demonstrates the use of range based for loop in our C++ programs:

Iterate over an Array using Range Based for Loop

C++

//Driver Code Starts{ #include <iostream> using namespace std;  //Driver Code Ends }  int main() {     int arr[] = {1, 2, 3, 4, 5};   	   	// Range based for loop to iterate over array   	// and i is used to represent each element      for (int i : arr) {         cout << i << " ";     }  //Driver Code Starts{      return 0; } //Driver Code Ends }

Output

1 2 3 4 5

Iterate over a Map using Range Based for Loop

Each element of the map is a pair of the same type as that of a map. We have to specify that in declaration, or we can use auto keyword.

C++

#include <bits/stdc++.h> using namespace std;  int main() {     map<int, char> m = {{1, 'A'}, {2, 'B'}, {3, 'C'},                   {4, 'D'}, {5, 'E'}};   	   	// Range based for loop to iterate over array   	// and i is used to represent each element      for (auto p: m) {         cout << p.first << ": " << p.second << endl;     }      return 0; }

Output

1: A 2: B 3: C 4: D 5: E

Since C++ 17, there is also another method of declaration of range based for loop.

C++ 17

#include <bits/stdc++.h> using namespace std;  int main() {     map<int, char> m = {{1, 'A'}, {2, 'B'}, {3, 'C'},                   {4, 'D'}, {5, 'E'}};   	   	// Range based for loop to iterate over array   	// and i is used to represent each element      for (auto [k, v]: m) {         cout << k << ": " << v << endl;     }      return 0; }

Output

1: A
2: B
3: C
4: D
5: E

Iterate Vector by Reference using Range Based for Loop

By default, the variable that represents each element is a copy of the element. We cannot make changes in actual range using that variable. In this case, we have to declare it as a reference as shown in the below program.

C++

#include <bits/stdc++.h> using namespace std;  int main() {     vector<int> v = {1, 2, 3, 4, 5};      	// Increment each element   	for (auto i: v) {       	i++;     }      	// Increment each element using reference   	for (auto& i: v) {       	i++;     }      // Iterating through vector     for (auto& i : v)         cout << i << " ";        return 0; }

Output

2 3 4 5 6

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Range-Based for Loop in C++

Syntax of Range Based for Loop

Examples of Range Based for Loop

Iterate over an Array using Range Based for Loop

Iterate over a Map using Range Based for Loop

Iterate Vector by Reference using Range Based for Loop

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