Else clause on Python while statement

Question

I\'ve noticed the following code is legal in Python. My question is why? Is there a specific reason?

n = 5
while n != 0:
    print n
    n -= 1
else:
    pri         


        

Answer 1

The else clause is only executed when the while-condition becomes false.

Here are some examples:

Example 1: Initially the condition is false, so else-clause is executed.

i = 99999999

while i < 5:
    print(i)
    i += 1
else:
    print('this')

OUTPUT:

this

Example 2: The while-condition i < 5 never became false because i == 3 breaks the loop, so else-clause was not executed.

i = 0

while i < 5:
    print(i)
    if i == 3:
        break
    i += 1
else:
    print('this')

OUTPUT:

0
1
2
3

Example 3: The while-condition i < 5 became false when i was 5, so else-clause was executed.

i = 0

while i < 5:
    print(i)
    i += 1
else:
    print('this')

OUTPUT:

0
1
2
3
4
this