A do-while loop always executes its body at least once.

Question

BlackTom AI · Accepted Answer

A do-while loop executes its body first and evaluates the loop condition afterward, so the body always runs at least once.

1. Relevant knowledge points and concepts
- Control flow for loops: while vs do-while.
- In a while loop the condition is checked before the body; in a do-while the condition is checked after the body.
- Common languages (C, C++, Java, JavaScript, PHP) implement do-while with this postcondition check semantics.

2. Step-by-step reasoning process
- Initialization: any loop variables are set before entering the loop.
- Execution step 1: execute the loop body unconditionally the first time.
- Execution step 2: evaluate the loop condition (boolean expression).
  - If condition is true, repeat step 1.
  - If condition is false, exit the loop.

3. Execution trace example (showing intermediate steps)
Example in pseudocode:
int x = 5;
do {
  print(x);          // Step A: body executes -> prints 5
  x = x - 1;
} while (x > 10);     // Step B: condition evaluated -> 4 > 10 is false
Result: The body executed once (printed 5), then condition false, loop ends.

4. Why the correct answer is correct
Because the condition is evaluated after the body in a do-while construct, there is no possibility to skip the first execution of the body. Even if the condition is false initially, the body runs once before that false evaluation.

5. Why the other option (False) is incorrect
Answer "False" would claim the do-while body might not execute at all. That describes a pre-test loop (while) rather than a post-test loop (do-while). In a standard do-while, skipping the entire body on the first pass cannot happen.

6. Conclusion
The statement is True. This matches the provided answer: True.

A do-while loop always executes its body at least once.判断题

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