how to convert a string to a double c++

To convert a string to a double in C++, you can use the std::stod() function. Here are the steps to do it:

1. Include the necessary header file:

#include <string>

1. Create a string variable containing the string you want to convert:

std::string str = "3.14";

1. Use the std::stod() function to convert the string to a double:

double value = std::stod(str);

1. The variable value will now hold the converted double value.

Here's the complete code example:

#include <iostream>
#include <string>

int main() {
    std::string str = "3.14";
    double value = std::stod(str);
    std::cout << "Converted value: " << value << std::endl;
    return 0;
}

This code will output:

Converted value: 3.14

And that's how you can convert a string to a double in C++ using the std::stod() function.