Mastering C++: A Comprehensive Quiz Based on 'Thinking in C++'

What is required for a do-while loop to execute its code block at least once?

1. The condition must be true at the beginning

2. The condition is checked at the end of each iteration

3. A specific number of iterations must be set beforehand

4. The loop does not require any condition to run at least once

The correct answer is: The condition is checked at the end of each iteration

A do-while loop executes its code block at least once because the condition is checked at the end of each iteration. This means that the code block will always be executed at least once, regardless of the initial value of the condition. The other options are incorrect because A requires the condition to be true initially, C requires a specific number of iterations to be set beforehand, and D is incorrect because the loop does require a condition to run.