Thread: question about the loop in case conversion program

I've got a little tip for you to make your algorithm much cleaner. In ASCII code, the only difference between a letter and the same letter of the opposite case is the fifth bit of the character. Upper case numbers have a fifth bit value of 0, lower case of 1, and the rest of the bits are the same. So to change the case of a letter, all you need to do is flip the fifth bit of the number. How do you do that? With the binary exclusive OR operator (^). If you don't know about binary operators or the exclusive or operation, look them up. At any rate, here's my revision of your code:

Code:

// C++ A Beginer's Guide - Herbert Schildt
// Module 3 Mastery Check Question # 11

// Case Converter

#include <iostream>

using namespace std;

int main()
{
	cout << "Case Converter\n\n";
	cout << "Please type something (enter a \'.\' to quit):\n\n";

	char input;
	int caseCounter = 0;  // records number of coversions

	while (input != '.')
	{
		cin >> input;

		if( input >= 'A' && input <= 'z' )
		{
			input ^= 1 << 5; //Flip the fifth bit of the char
			caseCounter++;
		}
		
		cout <<input;
	}
	
	cout << "\n\nThe number of case changes was: " 
                << caseCounter << "\n\n";
}

Oooh, clean. If you didn't know, the << operator is used as the binary shift operator(google it )