Unsure how many times to repeat code?

Python has the while keyword. Unlike the for loop which tests the condition first, the while loop execute the code first. Sometimes we don’t know how long sometimes will take.

A theoretical program could be (pseudocode):

while sun_not_shining:
use jacket
use gloves
which keeps executing the code block until the condition is true.

Related Course:

while loop example

Lets build an extended ‘guess the number game’:

 x = 0
while x != 5:
x = int(input("Guess a number:"))

if x != 5:
print("Incorrect choice")

print("Correct")
This will keep asking a number until the number is guessed. This is defined in the line: while x != 5, or in English, “while x is not equal to five, execute”.

Illustrated:

python while loop control flow

The program keeps repeating the code block while the condition (x!=5) is True. Once x equals 5, the program continues.

Infinite loop

If a condition in a while loop is never met, it could cause the program to run forever or to freeze/crash.
 
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