Command line arguments example in C

25 Apr, 2022
Prerequisite: Command_line_argument. The problem is to find the largest integer among the three using command line arguments. Notes:
Command-line arguments are given after the name of the program in the command-line shell of Operating Systems. To pass command line arguments, we typically define main() with two arguments: the first argument is the number of command-line arguments and the second is a list of command-line arguments.
int main(int argc, char *argv[]) { /* ... */ }
atoi – Used to convert string numbers 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
When calling the program, we pass three integers along with its filename, and then the program prints out the largest of the three numbers. Approach:
The program “return 1” if one of the two following conditions is satisfied:If any two numbers are the same, print the statement “two equal numbers entered”.If any of the numbers is negative, print “negative number entered”.Else “return 0” if three different integers are entered.
The program “return 1” if one of the two following conditions is satisfied:If any two numbers are the same, print the statement “two equal numbers entered”.If any of the numbers is negative, print “negative number entered”.
If any two numbers are the same, print the statement “two equal numbers entered”.
If any of the numbers is negative, print “negative number entered”.
Else “return 0” if three different integers are entered.
For better understanding, run this code for yourself.
C
// C program for finding the largest integer// among three numbers using command line arguments#include <stdio.h>#include <stdlib.h> // Taking argument as command lineint 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 :
   
vbsesa7h62yn5zrw0sff53coo6p9d08z1cxjkhky
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