While loop assignment

Question

# Finicky Counter
# Demonstrates the break and continue statements

count = 0
while True:
  count += 1
  # end loop if count greater than 10
  if count > 10:
   break
  # skip 5
  if count == 5:
    continue
  print(count)

input("\n\nPress the enter key to exit.")

Why does the while True loop apply to count in this circumstance? I dont understand why the boolean is gauging the result of count. Wouldn't the correct syntax be:

while count:

Any help clarifying this would be appreciated.

Answer 1

count is 0, so while count would never even enter the loop, since 0 is False in a boolean context.

Python doesn't have a construct similar to the repeat ... until (condition) found in some other languages. So if you want a loop to always start, but only end when a condition becomes true, the usual way to do it is to set the condition to just True - which, obviously, is always true - and then explicitly test the condition inside the loop, and break out using break .

To answer your comment, the thing that's true here is simply the value True , which as I say will always be the case.

Answer 2

It helps if you follow the code step-by-step in a debugger (a simple ide which allows this is PyScripter).

Just a few remarks:

• while True is an endless loop. It can only be left by a break or return statement.
• therefore the loop will run until the condition count > 10 is met. The break will terminate the loop and the next command ( input ... ) is executed.
• if count == 5 , continue tells python to jump immediately to the beginning of the loop without executing the following statement (therefore the "5" ist not printed).

But: follow the code in a debugger!

Answer 3

The syntax for a while loop is "while condition ." The block beneath the while loop executes until either condition evaluates to False or a break command is executed. "while True" means the condition always is True and the loop won't stop unless a break is execute. It's a frequent python idiom used since python doesn't have a do while loop.