Convert Float to String In C++

Last Updated : 27 Nov, 2022

In this article, we learn how we can convert float to string in C++ using different methods:

Using the to_string()
Using stringstream
Using Macros
Using lexical_cast from the boost library

1. Using to_string()

The to_string() method takes a single integer variable or other data type and converts it into a string.

Syntax: -

string to_string (float value);

Example:

C++

#include <bits/stdc++.h> using namespace std;  int main() {     float x=5.5;       string resultant;       resultant=to_string(x);     cout << "Converted value from float to String using to_string() is : "<<resultant<<endl;     return 0; }

Output

Converted value from float to String using to_string() is : 5.500000

Explanation: The to_string function converts the given float value into the string.

2. Using stringstream

A stringstream associates a string object with a stream allowing you to read from the string as if it were a stream (like cin). To use stringstream, we need to include sstream header file. The stringstream class is extremely useful in parsing input. The basic methods are:

clear() - To clear the stream.
str() - To get and set a string object whose content is present in the stream.
operator <<- Add a string to the stringstream object.
operator >>- Read something from the stringstream object.

Example:

C++

#include <bits/stdc++.h> using namespace std;  int main() {            float x=5.5;       stringstream s;       s<<x; // appending the float value to the streamclass       string result=s.str(); //converting the float value to string     cout <<"Converted value from float to String using stringstream is : "<<result<<endl;     return 0; }

Output

Converted value from float to String using stringstream is : 5.5

Explanation: The stringstream class converts the float value from a variable to a string. It is an inbuilt class present in the C++ Library.

3. Using Macros

This method solely applies to floating point conversion. The '#' is used by the STRING macro to convert the floating-point values to String.

Syntax:

#define STRING(Value) #Value  string gfg(STRING(Float_value));

Example:

C++

#include <bits/stdc++.h> #include <string> using namespace std; //using macro to convert float to string #define STRING(Value) #Value  int main() {     string gfg(STRING(5.5));     if(gfg.empty()) cout << "The String is empty"<<endl ;     else cout << gfg << endl;      return EXIT_SUCCESS; }

Output

5.5

4. Using lexical_cast

Boost.LexicalCast which is defined in the Library "boost/lexical_cast.hpp" provides a cast operator, boost::lexical_cast, that can convert numbers from strings to numeric types like int or double and vice versa. boost::lexical_cast is an alternative to functions like std::stoi(), std::stod(), and std::to_string(), which were added to the standard library in C++11.

Syntax:

float x= 5.5;  string res = lexical_cast<string>(x);

Example:

C++

#include "boost/lexical_cast.hpp" #include <bits/stdc++.h> using namespace std; using boost::lexical_cast; using boost::bad_lexical_cast; int main() {    // Float to string conversion   float x= 5.5;   string res = lexical_cast<string>(x);   cout << res << endl;   return 0; }