C tutorial

Command Line Argument in C

Command line argument is a parameter supplied to the program when it is invoked. Command line argument is an important concept in C programming. It is mostly used when you need to control your program from outside. Command line arguments are passed to the main() method.

Syntax:

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

Here argc counts the number of arguments on the command line and argv[ ] is a pointer array which holds pointers of type char which points to the arguments passed to the program.

Example for Command Line Argument

#include <stdio.h>
#include <conio.h>

int main(int argc, char *argv[])
{
    int i;
    if( argc >= 2 )
    {
        printf("The arguments supplied are:\n");
        for(i = 1; i < argc; i++)
        {
            printf("%s\t", argv[i]);
        }
    }
    else
    {
        printf("argument list is empty.\n");
    }
    return 0;
}

Remember that argv[0] holds the name of the program and argv[1] points to the first command line argument and argv[n] gives the last argument. If no argument is supplied, argc will be 1.