How to Write a Command Line Program in C?
Last Updated :
24 Apr, 2025
In C, we can provide arguments to a program while running it from the command line interface. These arguments are called command-line arguments. In this article, we will learn how to write a command line program in C.
How to Write a Command Line Program in C?
Command line arguments are passed to the main() function. For that purpose, the main function should have the following signature:
int main( int argc , char *argv[] ){
// Write your code
}
Here, argc is the number of arguments, and argv[] is the argument in the form of an array of strings.
Note: The argv[0] always contains the source file name.
C Program to Pass Command Line Arguments
C
// Program to demonstrate Command line arguments in C
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char* argv[])
{
// code to calculate the sum of n numbers passed to CLA
int i, sum = 0;
// iterating the loop till the the number of
// command-line arguments passed to the program
// starting from index 1
for (i = 1; i < argc; i++) {
sum = sum + atoi(argv[i]);
}
printf("Sum of %d numbers is : %d\n", argc - 1, sum);
return 0;
}