Question

Write a program that will accept two integers on command line, use the swap subprogram to swap them, and then print the two numbers out. For example, I enter a.out 10 15 and the output that would print is 15 10. Please note that if exactly two numbers are not provided on command line, your program should display an error message and end with no further action. The programming language is C Compiler.

Answer 1

// C program to swap the two numbers using command line arguments

#include<stdio.h>

#include<stdlib.h> /*atoi*/

// Function to swap the two numbers that is 'x' and 'y'

void swap(int x, int y)

{

x=x+y;

y=x-y;

x=x-y;

printf("%d %d",x,y);   

}

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

// Check if length of args array is 1

if (argc==1)

{

printf("No command line arguments found. \n");

}

else

{

// Get the command line argument and Convert it from string type to integer type using function "atoi( argument)"
num1 = atoi(argv[1]);
num2 = atoi(argv[2]);

swap(num1, num2); // Swap the numbers and print it

}

return 0;

}

Steps to execute program using command line:

1. First install tmd gcc compiler

2. Open cmd and go through the folder where you saved your c program. In my case i have created a folder named HomeworkLib at Desktop, inside this folder, swap.c is my c program

3. Now type : gcc swap.c and press enter

4. After successfully running this line on cmd, a.exe file is created in folder

5. Now type : a.exe 15 25 and press enter.

6. You will get output as 25 15

Screenshot of the folder created :

Screenshot of cmd :