While Loops
Loops are used to iterate through the same block of code multiple times. A for
loop will keep executing the same block of code until it has iterated through the entire iterable (list, dictionary or tuple).
while
loops are different than for
loops. A while
loop will keep running a block of code repeatedly until a specified condition becomes False
. The skeleton for a while
loop is as follows:
while (condition): //execute code
In this article, you're going to learn how to use while loops to repeatedly execute a block of code based on a condition.
While loops in action
You will start by defining a while
loop that keeps printing a random number while the random number remains less than 30
random_number = 25 while random_number < 30: print(random_number)
>>20
>>20
>>20
>>.......
The code runs forever! Stop the code's execution from the Runtime menu.
The code runs forever because the while loop is configured to keep running while random_number is less than 30. The condition random_number < 30
will always be True
since random_number
will always be equal to 25.
This can be fixed by incrementing random_number
by 1 in each iteration.
while random_number < 30: random_number += 1 print(random_number)
>>26
>>27
>>28
>>29
>>30
In each iteration, random_number
is incremented by 1 until it reaches 30. random_number
eventually becomes large enough to render the condition False
, breaking the while
loop.
That wraps it up for while
loops. They are as simple as they seem!
In summary, a while
loop will repeatedly execute a block of code until its condition stops being met. Try playing around with the condition and see what type of results you get!