Question 19

What is the output of the following code?

i, x = 0, 20
count = 0
while i < x:
    i += 2
    count += 1
print(count)

Hint

Trace the values of i, x, and count carefully as you run through the loop structure.

Solution

i	i < x?	New i: i += 2	count
0	0 < 20 (True)	0 + 2 = 2	0 + 1 = 1
2	2 < 20 (True)	2 + 2 = 4	1 + 1 = 2
4	4 < 20 (True)	4 + 2 = 6	2 + 1 = 3
6	6 < 20 (True)	6 + 2 = 8	3 + 1 = 4
8	8 < 20 (True)	8 + 2 = 10	4 + 1 = 5
10	10 < 20 (True)	10 + 2 = 12	5 + 1 = 6
12	12 < 20 (True)	12 + 2 = 14	6 + 1 = 7
14	14 < 20 (True)	14 + 2 = 16	7 + 1 = 8
16	16 < 20 (True)	16 + 2 = 18	8 + 1 = 9
18	18 < 20 (True)	18 + 2 = 20	9 + 1 = 10
20	20 < 20 (False)

Answer

10