It is used to read data from user using main function.
Example
Write a Program to add 2 numbers using CLA
Output
#include<stdio.h>
void main(int argc , char * argv[])
{
int i,sum=0;
if(argc!=3)
{
printf("you have forgot to type numbers.");
exit(1);
}
printf("The sum is : ");
for(i=1;i<argc;i++)
sum = sum + atoi(argv[i]);
printf("%d",sum);
}