Computer Science – 11.2 Constructs | e-Consult

Key Difference:

The key difference lies in when the loop condition is checked. A pre-condition loop checks the condition before each iteration. If the condition is false, the loop body is never executed. A post-condition loop checks the condition after each iteration. The loop body is always executed at least once, and then the condition is checked to determine if the loop should continue.

Pre-condition Example: Validating user input. As shown in the previous question, a pre-condition loop is ideal when you need to ensure a certain condition is met before proceeding with a task. If the condition isn't met, the task isn't started.

Post-condition Example: Iterating until a desired state is achieved. For example, repeatedly attempting to connect to a network until the connection is successful. The connection attempt (loop body) is always performed, and the condition checks if the connection is successful after each attempt.