Command Line Arguments are values passed to a program when it is executed from the command line. They allow users to provide input without using functions like scanf().

Syntax

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

or

int main(int argc, char **argv)

Explanation

  • argc (Argument Count): Stores the total number of command-line arguments, including the program name.
  • argv (Argument Vector): An array of strings containing the command-line arguments.
    • argv[0] → Program name
    • argv[1] → First argument
    • argv[2] → Second argument, and so on.

Example Program

#include <stdio.h>

int main(int argc, char *argv[])
{
    int i;

    printf("Total Arguments = %d\n", argc);

    for(i = 0; i < argc; i++)
    {
        printf("Argument %d = %s\n", i, argv[i]);
    }

    return 0;
}

Sample Execution

Compile:

gcc cmd.c -o cmd

Run:

./cmd Hello World 123

Output

Total Arguments = 4
Argument 0 = ./cmd
Argument 1 = Hello
Argument 2 = World
Argument 3 = 123

Example: Adding Two Numbers Using Command Line Arguments

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
    if(argc != 3)
    {
        printf("Usage: %s num1 num2\n", argv[0]);
        return 1;
    }

    int a = atoi(argv[1]);
    int b = atoi(argv[2]);

    printf("Sum = %d\n", a + b);

    return 0;
}

Sample Execution

./cmd 10 20

Output:

Sum = 30

Advantages

  • Easy to pass input while running the program.
  • Useful for automation and shell scripting.
  • Eliminates the need for interactive input (scanf).

Category: MCA

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