Thread: Testing ~bit

I am a little confused on how to test user input with the correct answer of a complementary bit. A labby told us just to AND it with 255, but I do not understand why we are doing that.

byte1 is an randomly generated unsigned char from 0 - 255
userInput is an intiger

Code:

// Asks for answer of ~byte1
	con << "What is the COMPLEMENT result of " << int(byte1) << " ("; toBin(byte1); con << ")?\n";
	con << "> ";
	if(!(cin >> userInput))
	{
		cin.clear();
		cin.ignore(20, '\n');
		con << "Bad Input! Incorrect Answer.\n";
	}
	else 
	{
		// Checks to see if the answer is correct
		if (userInput == (~byte1 & 255))
		{
			numCorrect++;
			con << "Correct!\n";
		}
		else
			con << "False!\n";

		cin.ignore(20, '\n');
	}