c++ string to float

To convert a C++ string to a float, you can use the `std::stof` function from the `<string>` library. Here's an example:

#include <iostream>
#include <string>

int main() {
    std::string str = "3.14";
    float floatValue = std::stof(str);
    
    std::cout << "Float value: " << floatValue << std::endl;
    
    return 0;
}

In this example, the `std::stof` function takes the string `str` and converts it to a float value. The resulting float value can then be used as needed.