Ceasar pset2, checking number of command-line arguments

Question

So I'm working on the first part of Caesar and this is what i have so far :

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

int main (int argc, string argv[])
{
    if (argc == 1)
    {
        printf ("Success");
    }
    else
    {
        printf ("Usage: ./ceasar key");
    }
}

This is clearly wrong since it won't work but i don't know how to check the number of command-line arguments without having to actually use string argv[]. The program seems to demand that if I'm to enter another argument then I have to also use it in the program but at this stage I don't want to, I just want to check that it exists without printing it. What am I doing wrong ?

Answer 1

argv[0] is the name of the executable itself (might be empty string if name is not available), so the first parameter would be argv[1], meaning you have to check for argc being 2, not 1.

Edit: I misread your question. You need to use all variables. A very simple way is to typecast the variable to void, which is always possible:

int main(int argc, char* argv[])
{
    printf("argc is %i\n", argc);
    (void)argv; // does nothing, but it "uses" the variable
}