C++ Recursion: Reversing a string using recursive function

C++ Recursion: Exercise-6 with Solution

Write a C++ program to reverse a string using recursion.

Sample Solution:

C Code:

// Recursive function to reverse a string
#include <iostream> // Including the Input/Output Stream Library
#include <string> // Including the String Library

// Recursive function to reverse a string
void reverse_String(std::string & text, int start, int end) {
  // Base case: when start >= end, the string is fully reversed
  if (start >= end)
    return;

  // Swap characters at start and end indices
  std::swap(text[start], text[end]);

  // Recursive case: move to the next pair of characters
  reverse_String(text, start + 1, end - 1);
}

int main() {
  std::string text; // Declaring a string variable to store user input
  std::cout << "Input a string: ";
  std::getline(std::cin, text); // Taking a string input from the user

  // Reverse the string using recursion
  reverse_String(text, 0, text.length() - 1);

  std::cout << "Reversed string: " << text << std::endl; // Displaying the reversed string

  return 0; // Returning 0 to indicate successful execution of the program
}

Sample Output:

Input a string: C++
Reversed string: ++C

Input a string: String
Reversed string: gnirtS

Input a string: madam
Reversed string: madam

Explanation:

In the above exercise,

• The "reverse_String()" function takes a reference to a string (str), the starting index (start), and the ending index (end) as parameters.
• Use recursion to reverse the string. The base case is when start >= end, indicating the string is fully reversed.
• In the recursive case, the function swaps the characters at the start and end indices using the std::swap function and then recursively calls the "reverse_String()" function for the next pair of characters (start + 1 and end - 1).
• The "main()" function prompts the user to enter a string, calls "reverse_String()" to reverse the string, and then displays the reversed string.

Flowchart:

CPP Code Editor:

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