just a little noob problem. I stopped learning C++ for a while but have just got back into it, so I thought I'd do a little program to check I'm ok with basic stuff.

Anyway here it is, it's just a small maths game, but when I compile it (Borland Compiler) it says the variables 'guess' and 'answer' arn't used in the function main... When I'm pretty sure they are


Well, here's the code:
Code:
#include <iostream>

using namespace std;

int main()
{
	int answer = 1, guess = 1, x = 1;
	
	cout << "\n\n-----------------------------------\nSelect Difficulty\n1 - Easy\n2 - Medium\n3 - Hard\n4 - Quit\n\nChoice: ";
	cin >> x;
	
		switch(x)
		{
			case 1:
				answer = 20;
				while(guess ! = answer)
				{
					cout << "(27 + 13) / 2 = ";
					cin >> guess;
					if(guess ! = answer)
						cout << "Wrong!";
				}
				cout << "Correct!";
				break;
					
			case 2:
				answer = 170;
				while(guess ! = answer)
				{
					cout << "(18 + 36) * 3 + 8 = ";
					cin >> guess;
					if(guess ! = answer)
						cout << "Wrong!";
				}
				cout << "Correct!";
				break;
				
			case 3:
				answer = 360;
				while(guess ! = answer)
				{
					cout << "(84 + 23 - 7) * 3.5 + (36 / 6 + 4) = ";
					cin >> guess;
					if(guess ! = answer)
						cout << "Wrong!";
				}
				cout << "Correct!";
				break;
			
			case 4:
				cout << "End of program.";
				break;
				
			default:
				cout << "Error: That is not an option";
		}
}

Thanks if anyone can show me where I'm going wrong