Question

How to add or subtract the value of string? For example:

    std::string number_string;
    std::string total;

    cout << "Enter value to add";
    std::getline(std::cin, number_string;
    total = number_string + number_string;
    cout << total;

This just append the string so this won’t work. I know I can use int data type but I need to use string.

Answer 1

You can use atoi(number_string.c_str()) to convert the string to an integer.

If you are concerned about properly handling non-numeric input, strtol is a better choice, albeit a little more wordy. http://www.cplusplus.com/reference/cstdlib/strtol/