Truth Tables

A truth table shows how a logical expression is evaluated. This is the truth table for a logical and:

&&	true	false
true	true	false
false	false	false

The first column represents the first term in the logical expression, the first row represents the second term. The intersection represents the result. So:

(true && true) evaluates to true
(true && false) evaluates to false
(false && true) evaluates to false
(false && false) evaluates to false

This is a truth table for a logical or:

This is a truth table for a logical eor (exclusive or):

This is a truth table for a logical not (also called logical negation):

When writing your logical expressions, it is a good idea to make them as simple as possible and try to use positive logic rather than negative. For instance, the logical expression (!(x > 0)) can be re-written without the not as (x <= 0).