C produce error if no argument is given in command line

ccommand linescanf

In C, how can I produce an error if no arguments are given on the command line? I'm not using int main(int argc , * char[] argv). my main has no input so I'm getting my variable using scanf("%d", input)

Best Answer

Your question is inconsistent: if you want to get arguments from the command line, you must define main with argc and argv.

Your prototype for main is incorrect, it should be:

int main(int argc, char *argv[])

If the program is run without any command line arguments, arc will have the value 1. You can test it this way:

int main(int argc, char *argv[]) {
    if (argc < 2) {
        printf("error: missing command line arguments\n");
        return 1;
    }
    ...
}

If you define main with int main(void) you have no portable access to command line arguments. Reading standard input has nothing to do with command line arguments.

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