Else Statement and Loops¶
You can use an else statement after a for or while loop. The code in this else statement is executed if the loop completed without being terminated.
for i in range(3):
print(i)
else:
print('Loop completed')
0
1
2
Loop completed
The only time the else part will not be executed is if you break out of a loop:
for i in range(5):
print(i)
if i == 3:
break
else:
print('Loop completed')
0
1
2
3
Worked Example
A common use for this structure is if you’re searching for an object. Consider this example where we are trying to find a 'fish' in a list:
animals = ['zebra', 'cow', 'crow', 'eel']
for animal in animals:
if animal == 'fish':
print('We caught a fish!')
break
else:
print('We did not catch a fish.')
We did not catch a fish.
animals = ['human', 'bear', 'fish', 'squid', 'crab']
for animal in animals:
if animal == 'fish':
print('We caught a fish!')
break
else:
print('We did not catch a fish.')
We caught a fish!
Of course, finding a particular object in a list is quicker and simpler using:
animals = animals = ['human', 'bear', 'fish', 'squid', 'crab']
if 'fish' in animals:
print('We caught a fish!')
else:
print('We did not catch a fish.')
We caught a fish!
but for more complex procedures this may not be an option.