Main argument input definitions

Question

Is it possible to use the main function to define what an input can be?

int main(int argc, string argv[])

For example, within the argv[], the number of arguments can be defined to 1, 2, 3, etc. Can they also be defined as +/-, < /=/ >, etc to be effective as limits to the command-line input from the user?

Answer 1

Sure, it is possible. But you will have to check if the arguments given to main are valid for your program, and also you will have to convert the arguments to the type you need, since the arguments are strings.

Example:

#include <stdio.h>
#include <cs50.h>
#include <string.h>

int main(int argc, char* argv[])
{
    if (argc == 1)
    {
        printf("Enter your name: ");
        string name = GetString();

        printf("Thanks, %s %d", name, argc);
    }
    else if (argc == 2)
    {
        if (argv[1][0] == 'a' && strlen(argv[1]) == 1)
        {
            printf("The argument is the letter a \n");
        }
        else if(argv[1][0] == 'b' && strlen(argv[1]) == 1)
        {
            printf("The argument is the letter b\n");
        }
        else
        {
            printf("Invalid argument\n");
        }
    }
    else
    {
        printf("Invalid number or arguments\n");
    }

    return 0;
}