// Mr. Minich
// CMPSC 201
// Ch. 4 Demo Program #4
// January 30, 2000 
// Purpose - to illustrate common errors related to the use of the C++ if statement

#include <iostream.h>

int main()
{
	int num1 = -5;  // used in if statement examples
	int num2 = 0;   // used in if statement examples

	if (num1)
	{  
		cout << "This prints if num1 is nonzero.\n";  
	}

 	// I recommend the use of curly braces in the statement above even though
	//   they are technically optional in this situation.
		
	if (num1 && num2)
		{
		   cout << "This prints if num1 AND num2 are both nonzero.\n";
		   cout << "This also prints if num1 AND num2 are both nonzero.\n";
		}

	// Here the curly braces are required since 2 or more statements are included in the 
	//   the conclusion of the if statement. 

	if (num1)
		cout << "This prints if num1 is nonzero.\n" << endl;

	if (num1 && num2)
		cout << "This prints if num1 AND num2 are both nonzero.\n";
		cout << "This prints ALSO if num1 AND num2 are both nonzero.\n";

	// This if statement has incorrect logic (and incorrect indentation). Since the programmer did not
	// use curly braces to surround the conclusion cout statements. The fact
	// that the second cout statement is indented does not cause it to be 
	// interpreted as part of the if statement. It turns out that the message

	//     This prints ALSO if num1 AND num2 are both nonzero   

	// always prints out no matter what the result of the control expression
	// (num1 && num2) may be.

	if (num1 == 0);

		cout << "This always prints out due to another logic error.\n";

	// Because of the semicolon after the control expression, the cout
	// statement is not treated as part of the if statement and is always
	// executed no matter what the result of (num1 == 0) may be. It is a 
	// common error to incorrectly place semicolons after control expressions
	// in if statements.

	return 0;
}// end of main