C++ String Exercises: Change every letter in a string with the next one

Last update on April 11 2025 12:47:49 (UTC/GMT +8 hours)

2. Replace Each Letter with the Next in the Alphabet

Write a C++ program to change every letter in a given string with the letter following it in the alphabet (i.e. a becomes b, p becomes q, z becomes a).

Visual Presentation:

Sample Solution:

C++ Code :

#include <iostream> // Including input/output stream library
#include <string>   // Including string library for string manipulation
using namespace std; // Using the standard namespace

// Function to change characters in a string to the next character in the ASCII sequence
string change_letter(string str) {

	int char_code; // Variable to store ASCII value of characters

	// Loop through each character in the string
	for (int x = 0; x < str.length(); x++)
	{
		char_code = int(str[x]); // Get ASCII value of the character

		// Check if the character is 'z', then change it to 'a'
		if (char_code == 122)
		{
			str[x] = char(97);
		}
		// Check if the character is 'Z', then change it to 'A'
		else if (char_code == 90)
		{
			str[x] = char(65);
		}
		// Check if the character is an uppercase or lowercase letter
		else if (char_code >= 65 && char_code <= 90 || char_code >= 97 && char_code <= 122)
		{
			str[x] = char(char_code + 1); // Change to the next character in the ASCII sequence
		}

	}

	return str; // Return the modified string
}

int main()
{
	cout << "Original string: w3resource"; // Displaying the original string
	cout << "\nNew string: " << change_letter("w3resource"); // Displaying the modified string

	cout << "\n\nOriginal string: Python"; // Displaying the original string
	cout << "\nNew string: " << change_letter("Python"); // Displaying the modified string

	return 0; // Returning 0 to indicate successful execution
}

Sample Output:

Original string: w3resource
New string: x3sftpvsdf

Original string: Python
New string: Qzuipo

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C++ program to shift every alphabet in a string by one position, wrapping 'z' to 'a', while preserving digits.
• Write a C++ program to implement a Caesar cipher with a shift of 1 for all alphabetical characters.
• Write a C++ program that reads a string and outputs the string with each letter replaced by its successor, keeping non-letters unchanged.
• Write a C++ program to transform a string by replacing every letter with the next one and then reverse the resulting string.

C++ Code Editor:

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Previous C++ Exercise: Reverse a given string.
Next C++ Exercise: Capitalize the first letter of each word of a string.