C Program to Reverse a Given String

This page contains a C program that reverses a given string. The program uses basic string manipulation techniques to achieve this task.

Program Explanation

The C program to reverse a string follows these steps:

1. Include necessary headers: Include the <stdio.h> and <string.h> headers for input/output functions and string manipulation functions.
2. Main Function: The main function is the entry point of the program.
3. Input String: Define a string that you want to reverse.
4. Reverse the String: Use a loop to reverse the string by swapping characters from the start and end.
5. Print the Result: Output the reversed string to the console.

C Program Code

/*
 * C program to reverse a given string.
 */
#include <stdio.h>
#include <string.h>

/**
 * Function to reverse a given string.
 * @param str the string to be reversed
 */
void reverseString(char* str) {
    int n = strlen(str); // Get the length of the string
    for (int i = 0; i < n / 2; i++) {
        // Swap characters from start and end
        char temp = str[i];
        str[i] = str[n - i - 1];
        str[n - i - 1] = temp;
    }
}

/**
 * Main function which is the entry point of the program.
 * @return 0 on successful execution
 */
int main() {
    // Define the string to be reversed
    char str[] = "Hello, World!";
    
    // Print the original string
    printf("Original String: %s\n", str);
    
    // Call the reverse function
    reverseString(str);
    
    // Print the reversed string
    printf("Reversed String: %s\n", str);
    
    return 0;
}

Program Details

The program contains the following:

• reverseString Function: This function takes a string as input and reverses it in place by swapping characters from the start and end.
• main Function: The entry point of the program where the string is defined, the reverse function is called, and the results are printed.

Running the Program

To run the program:

1. Save the code in a file named reverse_string.c.
2. Compile the program using the command: gcc reverse_string.c -o reverse_string.
3. Run the compiled program using the command: ./reverse_string.

Explanation of the C Program:

1. Header Inclusions: The program includes <stdio.h> for input/output functions and <string.h> for string manipulation functions.
2. reverseString Function:
   • Takes a character array (char* str) as input.
   • Calculates the length of the string using strlen().
   • Uses a loop to swap characters from the start and end of the string until the middle of the string is reached.
3. main Function:
   • Defines a string str to be reversed.
   • Prints the original string.
   • Calls the reverseString function to reverse the string.
   • Prints the reversed string.