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Python Python Basics (2015) Letter Game App Even or Odd Loop

Ahmet GULER
Ahmet GULER
7,181 Points
Posted by Ahmet GULER
Ahmet GULER
7,181 Points

what does it means 'while variable:' ?

Hello,

As start is a variable here. and there is no condition, i am confused. What does it means:

while start:

does it means ? while a variable named as 'start' exits? or while start == True or while start == False

So how many times this loop will iterate? what will make the condition false and break the loop ?

even.py 
import random

def even_odd(num):
    # If % 2 is 0, the number is even.
    # Since 0 is falsey, we have to invert it with not.
    return not num % 2

start = 5

while start:
  number = random.randint(1,99)
  if even_odd(number) == True:
    print("{} is even".format(number))
  else:
    print("{} is odd".format(number))
  start -= 1

5 Answers

Carlos Federico Puebla Larregle
Carlos Federico Puebla Larregle
21,073 Points
Carlos Federico Puebla Larregle
Carlos Federico Puebla Larregle
21,073 Points

It means that, while the variable "start" is "truthy" is going to execute the code inside that scope. If you notice, the variable start is decremented inside the while scope

  start -= 1

The while condition is going to be true until "start" is equal to 0. 0 falsy value any other number is a truthy value.

I hope that clarifies it a little bit.

Ahmet GULER
Ahmet GULER
7,181 Points
Ahmet GULER
Ahmet GULER
7,181 Points

I just have one more small question. then why doesn't it work when i replace the statement as:

while start == True

Carlos Federico Puebla Larregle
Carlos Federico Puebla Larregle
21,073 Points
Carlos Federico Puebla Larregle
Carlos Federico Puebla Larregle
21,073 Points

Be cause Python does not make "Type coercion". This means that when the variable "start" is equal to the number 5 is "truthy" but is not actually the boolean value "True".

Ahmet GULER
Ahmet GULER
7,181 Points
Ahmet GULER
Ahmet GULER
7,181 Points

ok. thanks for your quick and kind help.