Command Line Arguments With “-” Prefix

Question

I'm trying to write a program which I'll be able to start with custom arguments. Like in this example "program.exe -width 1920 -height 1080". I wrote a simple code, which should work.

#include <iostream>

int main(int argc, char* argv[])
{
    for (int i = 1; i < argc; i++)
    {
        if (argv[i] == "-width")
        {
            std::cout << "Width: " << argv[++i] << "\n";
        }
        else if (argv[i] == "-height")
        {
            std::cout << "Height: " << argv[++i] << "\n";
        }
    }

    return 0;
}

And this program doesn't work. It's not displaying anything. I also tried checking this code line by line with debugger, but when argv[i] == "-width" it just skips it.

Is there a way to fix it or there are just some other methods of doing this?

Answer 1

You are comparing pointers, not strings. To compare strings via == , you should use std::string .

Also you should check if the elements argv[++i] exists.

#include <iostream>
#include <string>

int main(int argc, char* argv[])
{
    for (int i = 1; i < argc; i++)
    {
        if (argv[i] == std::string("-width") && i + 1 < argc)
        {
            std::cout << "Width: " << argv[++i] << "\n";
        }
        else if (argv[i] == std::string("-height") && i + 1 < argc)
        {
            std::cout << "Height: " << argv[++i] << "\n";
        }
    }

    return 0;
}

Answer 2

You can also use the s suffix

cout << ("wilson" == "wilson"s) << endl;

output:

1