Boolean

A Boolean variable is one that can be either true or false. Sometimes this is represented as on or off, or, 1 or 0.

In a program, Boolean expressions are tested to decide what course of action to take. They are usually found in if statements and loops. For example, the following is a PHP snippet in which $isOK is a Boolean value:

($isOK)
{
    // do something
}

If $isOK evaluates to true, the statements inside the curly braces will be executed. If it evaluates to false, the statements within the curly braces will not be reached.

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