Convert Variable From String To Float In C++

Converting a variable from string to float in C++ is a fundamental programming skill. This article will provide you with a quick, simple, and beginner-friendly guide on how to accomplish this task using C++.

Code Snippet: Converting String to Float

Here’s a simple code snippet showing how to convert a string to a float in C++.

#include <iostream>
#include <string>
#include <sstream>

int main() {
    std::string str = "3.14";
    std::stringstream s(str);
    float f;
    s >> f;
    std::cout << "The floating point representation is: " << f;
    return 0;
}

Code Explanation: Converting String to Float

In this section, let’s break down what each line of the code is doing.

• First, we include the necessary libraries: iostream for basic input and output, string for string manipulation, and sstream for input/output of strings.

#include <iostream>
#include <string>
#include <sstream>

• Then, within the main function, we declare a string variable, ‘str’, for the number we want to convert to float and initialize it as “3.14”.

std::string str = "3.14";

• We create a stringstream object ‘s’ and initialize it with the string ‘str’. The stringstream class is a stream class to operate on strings, which is especially useful for conversions between numeric and string data.

std::stringstream s(str);

• We declare a float variable ‘f’. This variable will store the float equivalent of the string once the conversion is performed.

float f;

• Using the extraction operator ’>>’ on the stringstream object ‘s’, we convert the string into a float and assign it to the variable ‘f’.

s >> f;

• Finally, we output the value of ‘f’ to verify our conversion. The program should print “The floating point representation is: 3.14”.

std::cout << "The floating point representation is: " << f;
return 0;

This process demonstrates a simple and accessible method for converting a string variable to a float in C++.