{"id":725,"date":"2020-10-23T03:41:24","date_gmt":"2020-10-23T03:41:24","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=725"},"modified":"2025-03-31T04:08:28","modified_gmt":"2025-03-31T04:08:28","slug":"python-while-else","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/python-basics\/python-while-else\/","title":{"rendered":"Python while else"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about the Python while else<\/code> statement and how to use it effectively.<\/p>\n\n\n\n

Introduction to Python while else statement #<\/a><\/h2>\n\n\n\n

In Python, the while<\/a><\/code> statement may have an optional else<\/code> clause:<\/p>\n\n\n

while<\/span> condition:\n    # code block to run<\/span>\nelse<\/span>:\n    # else clause code block<\/span><\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
In this syntax, the condition<\/code> is checked at the beginning of each iteration. The code block inside the while<\/code> statement will execute as long as the condition<\/code> is True<\/code>.<\/p>\n\n\n\n
The following flowchart illustrates the while...else<\/code> clause:<\/p>\n\n\n
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\"\"<\/figure>\n<\/div>\n\n\n
If you’re familiar with other programming languages such as JavaScript<\/a>, Java, or C#, you’ll find that the else<\/code> clause is quite strange in the context of a loop.<\/p>\n\n\n\n
However, the while...else<\/code> clause turns out to be very useful in some cases. Let’s take a look at an example of using the while...else<\/code> statement.<\/p>\n\n\n\n
Python while…else statement example #<\/a><\/h2>\n\n\n\n
Suppose we have the following list of fruits where each fruit is a dictionary that consists of the fruit<\/code> name and qty<\/code> keys:<\/p>\n\n\n
basket = [\n    {'fruit'<\/span>: 'apple'<\/span>, 'qty'<\/span>: 20<\/span>},\n    {'fruit'<\/span>: 'banana'<\/span>, 'qty'<\/span>: 30<\/span>},\n    {'fruit'<\/span>: 'orange'<\/span>, 'qty'<\/span>: 10<\/span>}\n]<\/code><\/span>Code language:<\/span> JavaScript<\/span> (<\/span>javascript<\/span>)<\/span><\/small><\/pre>\n\n\n
We want to make a program that allows the users to enter a fruit name. Based on the input name, we’ll search for it from the basket<\/code> list and show its quantity if the fruit is on the list.<\/p>\n\n\n\n
In case the fruit is not found, we’ll allow users to enter the quantity for that fruit and add it to the list.<\/p>\n\n\n\n
The following program is the first attempt:<\/p>\n\n\n
basket = [\n    {'fruit'<\/span>: 'apple'<\/span>, 'qty'<\/span>: 20<\/span>},\n    {'fruit'<\/span>: 'banana'<\/span>, 'qty'<\/span>: 30<\/span>},\n    {'fruit'<\/span>: 'orange'<\/span>, 'qty'<\/span>: 10<\/span>}\n]\n\nfruit = input('Enter a fruit:'<\/span>)\n\nindex = 0<\/span>\nfound_it = False<\/span>\n\nwhile<\/span> index < len(basket):\n    item = basket[index]\n    # check the fruit name<\/span>\n    if<\/span> item['fruit'<\/span>] == fruit:\n        found_it = True<\/span>\n        print<\/span>(f\"The basket has {item['qty']} {item['fruit']}(s)\"<\/span>)\n        break<\/span>\n\n    index += 1<\/span>\n\nif<\/span> not found_it:\n    qty = int(input(f'Enter the qty for {fruit}:'<\/span>))\n    basket.append({'fruit'<\/span>: fruit, 'qty'<\/span>: qty})\n    print<\/span>(basket)<\/code><\/span>Code language:<\/span> PHP<\/span> (<\/span>php<\/span>)<\/span><\/small><\/pre>\n\n\n
Note that there’s better way to develop this program. The program in this example is solely for the demonstration purpose.<\/p>\n\n\n\n
How it works:<\/p>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n
When the condition<\/code> becomes False<\/code> and the loop runs normally, the else<\/code> clause will execute. However, if the loop is terminated prematurely by either a break<\/a><\/code> or return<\/code> statement, the else<\/code> clause won’t execute at all.<\/p>\n\n\n\n