Python Control Flow: Loops 3

Question 1

What does `enumerate(['a', 'b', 'c'])` yield when iterated?

Accepted Answer

(0, 'a'), (1, 'b'), (2, 'c')

Answer

`enumerate()` yields `(index, value)` tuples starting from index 0 by default.

Question 2

Which statement about nested loops is true?

Accepted Answer

`break` in the inner loop only exits the inner loop

Answer

`break` only exits the innermost loop containing it; the outer loop continues normally.

Question 3

What is the result of `sum(i for i in range(5))`?

Accepted Answer

10

Answer

`range(5)` is 0+1+2+3+4 = 10.

Question 4

How do you iterate over both keys and values of a dictionary `d` simultaneously?

Accepted Answer

`for k, v in d.items():`

Answer

`d.items()` returns key-value pairs as tuples, which can be unpacked in the loop header.

Question 5

What is the output of: `i = 0
while True:
    i += 1
    if i == 3: break
print(i)`?

Accepted Answer

3

Answer

The loop breaks when `i` becomes 3, so `print(i)` outputs 3.

Python Practice Test