Boolean operations in a programming language: AND

The idea

The Boolean operator AND combines two conditions and yields True only when both are True; if either is False the result is False. In a program, an expression such as age >= 18 AND hasTicket == True is evaluated by testing each side and combining them. A truth table with inputs A and B shows the single True row at A = True, B = True. AND is often used to guard an action so it runs only when every requirement is met, for example allowing entry only when a learner is enrolled AND has paid. Contrast this with OR, which needs only one True. When reading a multiple-choice question, evaluate each side separately, then apply the AND rule, and check whether the option matches the combined result rather than just one operand.

What earns the marks

• AND returns True only when both operands are True.
• If either operand is False, the whole AND expression is False.
• A truth table for A AND B has exactly one True outcome, at A = True and B = True.
• AND is used to require all conditions to be satisfied before an action runs.
• Evaluating an expression means testing each operand and then combining with the AND rule.

Common mistakes and how to put them right

• Assuming AND returns True when at least one operand is True.

  Put it right by stressing both must be True.

• Confusing AND with OR; correct by comparing their truth tables side by side.

• Evaluating only one operand and ignoring the other.

  Put it right by testing both before combining.

Exam tips

• Write out each operand's value before applying the AND rule.
• Recall the single True row of the AND truth table to check your answer.
• Eliminate options that would only be correct for OR.