Trust Coding : Programming: Write a recursive C program to find the reverse of a string using recursion.

Reverse a String Using Recursion in C

In this tutorial, we will write a recursive C program to reverse a string using recursion.

Problem Statement

Write a C program that reverses a string using a recursive function.

Concept of Recursion

Recursion is a process in which a function calls itself until a base condition is met.

To reverse a string recursively:

Print the last character first.
Then recursively call the function for the remaining string.
Stop when the null character ('\0') is reached.

C Program


#include <stdio.h>

void reverseString(char str[], int index) {
    // Base condition
    if (str[index] == '\0')
        return;

    // Recursive call
    reverseString(str, index + 1);

    // Print character during backtracking
    printf("%c", str[index]);
}

int main() {
    char str[100];

    printf("Enter a string: ");
    scanf("%s", str);

    printf("Reversed string: ");
    reverseString(str, 0);

    return 0;
}

Explanation

1. Function Definition

The function reverseString() takes:

The string
The current index position

2. Base Condition


if (str[index] == '\0')
    return;

When the null character is reached, recursion stops.

3. Recursive Call


reverseString(str, index + 1);

The function keeps calling itself until it reaches the end of the string.

4. Backtracking Step


printf("%c", str[index]);

Characters are printed while returning from recursion, which reverses the string.

Sample Input

Enter a string: hello

Output

Reversed string: olleh

Time Complexity

Each character is processed once. Therefore, the time complexity is O(n).

Trust Coding : Programming

Write a recursive C program to find the reverse of a string using recursion.