Dexter is planning to enter the following values into the program above (in the order shown). 5, 7, 3, 5, -1, 2 and 8. What will be displayed by the program?

Question

BlackTom AI · Accepted Answer

The program uses a sentinel value (-1) to stop reading values; any Amount equal to -1 is not added to Total. Relevant concepts: sentinel-controlled loop, initialization of an accumulator (Total ← 0), and that input read just before the while condition controls entry to the loop. Step-by-step reasoning and intermediate calculations: 1) Initialization: Total = 0. 2) First Input Amount = 5. Check while (5 <> -1) → true. Execute body: - Total ← Total + Amount = 0 + 5 = 5. - Input next Amount → 7. 3) Loop check (7 <> -1) → true. Body: - Total = 5 + 7 = 12. - Input next Amount → 3. 4) Loop check (3 <> -1) → true. Body: - Total = 12 + 3 = 15. - Input next Amount → 5. 5) Loop check (5 <> -1) → true. Body: - Total = 15 + 5 = 20. - Input next Amount → -1. 6) Loop check (-1 <> -1) → false. The loop ends immediately; the sentinel -1 is NOT added to Total. 7) Print Total → 20. Why the correct answer is correct: - The loop stops when Amount equals -1, and the loop body only runs when the condition is true. Thus all inputs up to but not including the -1 are summed. Any numbers entered after the sentinel (2 and 8 in the list) are never read by the program because it has already exited the loop and proceeds to print. Why the other options are incorrect: - a. 29: not produced by summing the processed inputs; even including later numbers would not give 29 (the full sum of all non-sentinel entries would be different). - b. 0: would be printed only if the first input were -1, which it is not. - c. "Amount": nonsensical as the program prints the numeric Total, not the variable name. Conclusion: The program prints 20, which matches choice d. 20.

Dexter is planning to enter the following values into the program above (in the order shown). 5, 7, 3, 5, -1, 2 and 8. What will be displayed by the program?单项选择题

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