else#

In loops for and while you may optionally use else block.

for/else#

In loop for:

block else is executed if loop has completed iteration of list
but it does not execute if break was applied in loop.

Example of loop for with else (block else is executed after loop for):

In [1]: for num in range(5):
   ....:     print(num)
   ....: else:
   ....:     print("Run out of numbers")
   ....:
0
1
2
3
4
Run out of numbers

An example of loop for with else and break in loop (because of break, block else is not applied):

In [2]: for num in range(5):
   ....:     if num == 3:
   ....:         break
   ....:     else:
   ....:         print(num)
   ....: else:
   ....:     print("Run out of numbers")
   ....:
0
1
2

Example of loop for with else and continue in loop (continue does not affect else block):

In [3]: for num in range(5):
   ....:     if num == 3:
   ....:         continue
   ....:     else:
   ....:         print(num)
   ....: else:
   ....:     print("Run out of numbers")
   ....:
0
1
2
4
Run out of numbers

while/else#

In loop while:

block else is executed if loop has completed iteration of list
but it does not execute if break was applied in loop.

Example of a loop while with else (block else runs after loop while):

In [4]: i = 0
In [5]: while i < 5:
   ....:     print(i)
   ....:     i += 1
   ....: else:
   ....:     print("The End")
   ....:
0
1
2
3
4
The End

An example of a loop while with else and break in loop (because of break, block else is not applied):

In [6]: i = 0

In [7]: while i < 5:
   ....:     if i == 3:
   ....:         break
   ....:     else:
   ....:         print(i)
   ....:         i += 1
   ....: else:
   ....:     print("The End")
   ....:
0
1
2