While statements

Another important evaluation tool is the while statement. It is used to perform an action while a condition is true; when the condition is false, the evaluation will stop. Note that the condition must become false, or the action will be performed forever, creating an "infinite loop" that will not stop until the Python interpreter is shut off externally. Here is an example of using a while loop to perform an action until a true condition becomes false:

>>> x = 0
>>> while x < 5:
      print x
      x+=1
0
1
2
3
4