Write a c program to swap the content of 2 variables entered through the command line using function and pointer

General
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write a c program to swap the content of 2 variables entered through the command line using function and pointer.

2

Write a C program to swap the content of two variables entered through the command line using function and pointer

Answer:
To write a C program that swaps the contents of two variables entered through the command line using a function and pointers, follow these steps:

  1. Include Necessary Headers:

    • The program will require the use of the standard input-output library and assertions for simple debugging.

  2. Function Definition to Swap Two Variables:

    • Use a function swap that takes two pointers as arguments and swaps the values they point to.

  3. Command-Line Argument Handling:

    • Parse the command-line arguments to retrieve the two numbers.

  4. Invoke the Swap Function:

    • Call the swap function, passing the addresses of the variables.

Here’s the complete code:

#include <stdio.h>
#include <stdlib.h>

// Function to swap two integer variables using pointers
void swap(int *a, int *b) {
    int temp = *a;
    *a = *b;
    *b = temp;
}

int main(int argc, char *argv[]) {
    // Ensure there are exactly two additional command-line arguments
    if (argc != 3) {
        printf("Usage: %s <number1> <number2>\n", argv[0]);
        return 1;
    }

    // Convert command-line arguments to integers
    int num1 = atoi(argv[1]);
    int num2 = atoi(argv[2]);

    // Print original values
    printf("Before swapping: num1 = %d, num2 = %d\n", num1, num2);

    // Call the swap function with pointers to num1 and num2
    swap(&num1, &num2);

    // Print swapped values
    printf("After swapping: num1 = %d, num2 = %d\n", num1, num2);

    return 0;
}

Explanation:

  1. Including Necessary Headers:

    • We include <stdio.h> for input/output functions and <stdlib.h> for the atoi function that converts strings to integers.

  2. Function Definition (swap):

    • The swap function takes two pointers to integers (int *a, int *b). It uses a temporary variable temp to swap the values of the variables pointed to by a and b.

  3. Command-Line Argument Handling:

    • The main function checks if the correct number of command-line arguments are provided (argc != 3 checks for exactly 2 additional arguments). If not, it prints a usage message and exits.
    • If arguments are correct, it converts them from strings to integers using atoi.

  4. Invoke the Swap Function:

    • The original values of num1 and num2 are printed.
    • The swap function is called with the addresses of num1 and num2 (&num1, &num2).
    • Finally, the swapped values are printed.

How to Run the Program:

  1. Save the program to a file named, for example, swap.c.
  2. Compile the program using a C compiler (e.g., gcc):
    gcc -o swap swap.c
  3. Run the program with two numbers as arguments:
    ./swap 5 10

Final Answer:
This swap.c program reads two integers from the command line, swaps their values using a function that takes pointers, and then prints the swapped values. This demonstrates the use of pointers and functions in C for variable manipulation.