Free PCEP Using the `else` block in loops Questions and Answers 1 — Questions and Answers
Question 1: What is the output of the following code? ```python for i in range(3): print(i) else: print('Done!') ```
- 0 1 2
- 0 1 2 Done! (Correct answer)
- Done!
- A syntax error occurs.
Correct answer: 0 1 2 Done!
The `else` block in a `for` loop executes only if the loop completes its entire iteration without being terminated by a `break` statement. In this case, the loop finishes normally, so 'Done!' is printed after the numbers 0, 1, and 2.
Question 2: What is the output of the following code? ```python for num in [1, 2, 3, 4]: if num == 3: break print(num) else: print('Finished.') ```
- 1 2 (Correct answer)
- 1 2 Finished.
- 1 2 3
- 1 2 3 Finished.
Correct answer: 1 2
The `break` statement terminates the loop when `num` is 3. Because the loop did not complete its full iteration, the `else` block is skipped entirely. Only the numbers before the `break` are printed.
Question 3: What is the output of this `while` loop? ```python i = 5 while i > 0: i -= 1 if i == 2: continue print(i) else: print('Loop over.') ```
- 4 3 1 0
- 4 3 1
- 4 3 1 0 Loop over. (Correct answer)
- 4 3 2 1 0 Loop over.
Correct answer: 4 3 1 0 Loop over.
The `continue` statement skips the current iteration but does not terminate the loop. The loop continues until `i` becomes 0, at which point the condition `i > 0` is false. Since the loop completed normally, the `else` block is executed.
Question 4: Under which circumstance is the `else` block of a loop NOT executed?
- When the loop condition becomes false.
- When a `break` statement is executed. (Correct answer)
- When a `continue` statement is executed.
- When the loop iterates over an empty sequence.
Correct answer: When a `break` statement is executed.
The primary purpose of the `else` block in a loop is to run code when the loop finishes its iterations naturally. If the loop is exited prematurely using a `break` statement, the `else` block is skipped.
Question 5: What will be printed to the console? ```python for char in 'PCEP': print(char) break else: print('End of string') ```
- P C E P End of string
- P End of string
- P (Correct answer)
- End of string
Correct answer: P
The loop starts with the first character 'P' and prints it. Immediately after, the `break` statement is encountered, which terminates the loop. Since the loop was terminated by `break`, the `else` block is not executed.
Question 6: Consider the following code. What is the output? ```python items = [] for item in items: print(item) else: print('No items found.') ```
- An error occurs.
- The program produces no output.
- No items found. (Correct answer)
- []
Correct answer: No items found.
When a `for` loop is given an empty sequence (like an empty list), it does not execute its body at all. It is considered to have completed 'normally' without any iterations. Therefore, the `else` block is executed.
Question 7: What is the output of this code snippet? ```python n = 3 while n > 0: n -= 1 print(n) else: if n == 0: print('Loop ended.') ```
- 2 1 0 Loop ended. (Correct answer)
- 3 2 1
- 2 1 0
- 3 2 1 Loop ended.
Correct answer: 2 1 0 Loop ended.
The `while` loop runs until `n` becomes 0. The loop prints 2, 1, and 0. When `n` is 0, the condition `n > 0` becomes false, and the loop terminates. Since it terminated normally, the `else` block is executed. Inside the `else` block, the condition `n == 0` is true, so 'Loop ended.' is printed.
Free PCEP Using the `else` block in loops Questions and Answers 1
What is the output of the following code?
```python
for i in range(3):
print(i)
else:
print('Done!')
```