The else Statement in a while Loop

In Python, the else block can be added to a while loop. The else block executes when the loop terminates normally, meaning the loop condition becomes False without encountering a break statement.

The else block runs when the loop condition becomes False, signifying the loop has completed all iterations.


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travel_list = ['Monako', 'Luxemburg', 'Liverpool', 'Barcelona', 'Munchen']

# Initialize index
i = 0

# Iterate through the destinations
while i < len(travel_list):
    print(travel_list[i])
    i += 1
else:
    print('All destinations have been listed!')

In this example, the while loop iterates through each destination in the travel_list and prints it. Once all destinations are listed, the condition i < len(travel_list) becomes False, triggering the else block, which confirms completion.

If the loop terminates with a break statement (e.g., when a specific city is found), the else block does not execute.


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# List of travel destinations
travel_list = ['Monako', 'Luxemburg', 'Liverpool', 'Barcelona', 'Munchen']

# Initialize index
i = 0

# Search for a specific destination
while i < len(travel_list):
    if travel_list[i] == 'Barcelona':
        break
    print(travel_list[i])
    i += 1
else: # This won't execute if break is triggered.
    print('All destinations have been listed!')

Here, the loop stops as soon as it finds 'Barcelona'. The else block is skipped because the loop does not terminate normally but is interrupted by the break statement.

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Section 2. Chapter 5