Command line arguments example in C

The problem is to find the largest integers among three using command line argument.

Notes:

Command-line arguments are given after the name of the program in command-line shell of Operating Systems. To pass command line arguments, we typically define main() with two arguments : first argument is the number of command line arguments and second is list of command-line arguments.

int main(int argc, char *argv[]) { /* ... */ }

atoi – Used to convert string number to integers

Examples:

Input  : filename 8 9 45
Output : 45 is largest

Input  : filename 8 9 9
Output : Two equal number entered

Input  : filename 8 -9 9
Output : negative number entered

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

During execution of program, we pass three integers along with filename of the program and then we will find the largest numbers among three.
Approach :

1. The program “return 1” if any of the two conditions satisfy:
   • If any two numbers are same, print the statement “two equal numbers entered”.
   • If any number is negative, print “negative number entered”.
2. Else “return 0” if three different integers are entered.

For better understanding run this code on your 

// C program for finding the largest integer // among three numbers using command line arguments #include<stdio.h>    // Taking argument as command line int main(int argc, char *argv[])  {     int a, b, c;        // Checking if number of argument is     // equal to 4 or not.     if (argc < 4 || argc > 5)      {         printf("enter 4 arguments only eg.\"filename arg1 arg2 arg3!!\"");         return 0;     }        // Converting string type to integer type     // using function "atoi( argument)"      a = atoi(argv[1]);      b = atoi(argv[2]);     c = atoi(argv[3]);        // Checking if all the numbers are positive of not     if (a < 0 || b < 0 || c < 0)      {         printf("enter only positive values in arguments !!");         return 1;     }        // Checking if all the numbers are different or not     if (!(a != b && b != c && a != c))      {         printf("please enter three different value ");         return 1;     }     else     {         // Checking condition for "a" to be largest         if (a > b && a > c)                          printf("%d is largest", a);            // Checking condition for "b" to be largest             else if (b > c && b > a)              printf ("%d is largest", b);            // Checking condition for "c" to be largest..         else if (c > a && c > b)              printf("%d is largest ",c);     }     return 0; }

Output :

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.