C++ String Exercises: Alternate the case of each letter in a string

Last update on April 11 2025 12:47:29 (UTC/GMT +8 hours)

42. Alternate the Case of Each Letter in a String

Write a C++ program that alternates the case of each letter in a given string of letters.
Pattern: First lowercase letter then uppercase letter and so on.

Test Data:
("JavaScript") -> "jAvAsCrIpT"
("Python") -> "pYtHoN"
("C++") -> "c++"

Sample Solution:

C++ Code:

#include <bits/stdc++.h> // Include all standard libraries

using namespace std; // Using the standard namespace

// Function to alternate the case of each letter in a given string
std::string test(std::string text) {
    std::string str; // Initialize an empty string to store the modified text
    int ctr = 0; // Initialize a counter variable

    // Loop through each character in the input text
    for (char ch : text) {
        if (ctr % 2 == 0) // If the counter is even
            str += tolower(ch); // Convert the character to lowercase and append to the result string
        if (ctr % 2 != 0) // If the counter is odd
            str += toupper(ch); // Convert the character to uppercase and append to the result string
        if (ch == ' ') // If the character is a space
            ctr++; // Increment the counter
        ctr++; // Increment the counter after every character
    }
    return str; // Return the modified string
}

int main() {
    // Test cases
    string text = "JavaScript";
    cout << "Original String: " << text;
    cout << "\nAlternate the case of each letter in the said string: " << test(text);

    text = "Python";
    cout << "\n\nOriginal String: " << text;
    cout << "\nAlternate the case of each letter in the said string: " << test(text);

    text = "C++";
    cout << "\n\nOriginal String: " << text;
    cout << "\nAlternate the case of each letter in the said string: " << test(text);
}

Sample Output:

Original String: JavaScript
Alternate the case of each letter in the said string: jAvAsCrIpT

Original String: Python
Alternate the case of each letter in the said string: pYtHoN

Original String: C++
Alternate the case of each letter in the said string: c++

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program to iterate over a string and alternate the case of each letter starting with lowercase for the first letter.
Write a C++ program that reads a string and toggles each alphabet’s case so that even-indexed letters become lowercase and odd-indexed become uppercase.
Write a C++ program to process a string and output a new string with alternating cases, using ASCII arithmetic to change letter cases.
Write a C++ program that takes an input string and produces an output where the case of letters alternates between lower and upper, ignoring non-alphabet characters.

C++ Code Editor:

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Previous C++ Exercise: Second occurrence of a string within another string.