C++ String Exercises: Check whether a string is uppercase or lowercase

C++ String: Exercise-31 with Solution

Write a C++ program to check if a given string contains only uppercase or only lowercase letters. Return "True" if the string is uppercase or lowercase, otherwise "False".

Sample Data:
("ABCDEF") -> “True”
("abcdef") -> “True”
("ABcDef") -> “False”

Sample Solution-1:

C++ Code:

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

using namespace std; // Using the standard namespace

// Function to check if the string is all uppercase or all lowercase
string test(string text) {
  for (int i = 1; i < text.size(); i++) { // Loop through the string starting from the second character
    // Check if the case of the first character is different from the current character
    if (isupper(text[0]) != isupper(text[i])) { // Check if the first character's case differs from the current character
      return "False"; // If cases differ, return "False" indicating it's not all uppercase or all lowercase
    }
  }
  return "True"; // If all characters have the same case, return "True" indicating it's all uppercase or all lowercase
}

int main() {
  string text = "ABCDEF"; // Test string containing all uppercase characters
  //string text = "abcdef"; // Test string containing all lowercase characters
  //string text = "ABcDef"; // Test string containing a mix of uppercase and lowercase characters
  cout << "Original string: " << text; // Display the original string
  cout << "\n\nCheck whether the said string is uppercase or lowercase: ";
  cout << test(text) << endl; // Call the function to check and display whether the string is all uppercase or all lowercase
}

Sample Output:

Original string: ABCDEF

Check whether the said string is uppercase or lowercase: True

Flowchart:

Sample Solution-2:

C++ Code:

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

using namespace std; // Using the standard namespace

// Function to check if the string is all uppercase or all lowercase
string test(string text) {
	// Check if the first character of the string is uppercase
	if (isupper(text[0])) { // If the first character is uppercase
		// Loop through each character in the string
		for (auto ch : text) {
			// If any character is not uppercase, return "False"
			if (!isupper(ch))
				return "False";
		}
	}

	// Check if the first character of the string is lowercase
	if (islower(text[0])) { // If the first character is lowercase
		// Loop through each character in the string
		for (auto ch : text) {
			// If any character is not lowercase, return "False"
			if (!islower(ch))
				return "False";
		}
	}

	// If all characters in the string match the case of the first character, return "True"
	return "True";
}

int main() {
	//string text ="ABCDEF"; // Test string containing all uppercase characters
	//string text ="abcdef"; // Test string containing all lowercase characters
	string text ="ABcDef"; // Test string containing a mix of uppercase and lowercase characters
	cout << "Original string: " << text; // Display the original string
	cout << "\n\nCheck whether the said string is uppercase or lowercase: ";
	cout << test(text) << endl; // Call the function to check and display whether the string is all uppercase or all lowercase
}

Sample Output:

Original string: ABcDef

Check whether the said string is uppercase or lowercase: False

Flowchart:

C++ Code Editor:

Contribute your code and comments through Disqus.

Previous C++ Exercise: Identify the missing letter in a string.