Controlling loop execution Flashcards

What will be the output of the following code snippet? ```python for i in range(5): if i == 3: break print(i, end=' ') ```

Answer: 0 1 2

The loop iterates through numbers from 0 to 4. The `print` statement executes for `i` values 0, 1, and 2. When `i` becomes 3, the `if` condition is met, and the `break` statement is executed, which terminates the loop immediately.

What is the output of this code? ```python for i in range(5): if i == 3: continue print(i, end=' ') ```

Answer: 0 1 2 4

The loop iterates from 0 to 4. When `i` is 3, the `if` condition is true, and the `continue` statement is executed. This statement skips the rest of the current iteration (the `print` statement) and proceeds to the next iteration (when `i` is 4).

What does the following code print? ```python i = 0 while i < 5: print(i, end=' ') i += 1 if i == 3: break ```

Answer: 0 1 2

The `while` loop starts with `i = 0`. It prints 0, then increments `i` to 1. It prints 1, increments `i` to 2. It prints 2, increments `i` to 3. Now the condition `i == 3` is true, and the `break` statement terminates the loop.

What is the output of this `while` loop? ```python i = 0 while i < 5: i += 1 if i == 3: continue print(i, end=' ') ```

Answer: 1 2 4 5

Inside the loop, `i` is incremented first. When `i` becomes 3, the `continue` statement is executed, skipping the `print(i)` for that iteration. The loop continues, printing the values 1, 2, 4, and 5.

What is the output of the following nested loop? ```python for i in range(2): for j in range(2): if i == j: break print((i, j), end=' ') ```

Answer: (1, 0)

The `break` statement only affects the innermost loop it is in. When `i` is 0, the inner loop runs for `j=0`. The condition `i == j` is true, so `break` is executed, and nothing is printed. When `i` is 1, the inner loop runs for `j=0`. The condition is false, so `(1, 0)` is printed. Then `j` becomes 1, the condition `i == j` is true, and the inner loop breaks.

What will be printed by this code? ```python for num in range(4): if num == 2: break else: print("Done") print(num) ```

Answer: 2

The `for` loop's `else` block is executed only if the loop completes its iterations without being terminated by a `break` statement. In this case, the loop breaks when `num` is 2. Therefore, the `else` block is skipped. The final `print(num)` statement prints the last value of `num` before the loop was exited, which is 2.

What is the output of the following code? ```python for i in range(2): print(f"Outer {i}") for j in range(2): if j == 1: continue print(f" Inner {j}") ```

Answer: Outer 0 Inner 0 Outer 1 Inner 0

The `continue` statement only skips the current iteration of the inner loop. For each outer loop iteration (`i=0` and `i=1`), the inner loop starts. When `j` is 0, it prints. When `j` is 1, the `continue` skips the print statement and the inner loop finishes, then the outer loop proceeds to its next iteration.