Python basics printing 1 to 100

Question

def gukan(count):     while count!=100:       print(count)       count=count+1; gukan(0) 

My question is: When I try to increment by 3 or 9 instead of 1 in count=count+1 I get an infinite loop - why is that?

Answer 1

The answers here have pointed out that because after incrementing count it doesn't equal exactly 100, then it keeps going as the criteria isn't met (it's likely you want < to say less than 100).

I'll just add that you should really be looking at Python's builtin range function which generates a sequence of integers from a starting value, up to (but not including) another value, and an optional step - so you can adjust from adding 1 or 3 or 9 at a time...

0-100 (but not including 100, defaults starting from 0 and stepping by 1):

for number in range(100):     print(number) 

0-100 (but not including and makes sure number doesn't go above 100) in steps of 3:

for number in range(0, 100, 3):     print(number) 

Answer 2

When you change count = count + 1 to count = count + 3 or count = count + 9, count will never be equal to 100. At the very best it'll be 99. That's not enough.

What you've got here is the classic case of infinite loop: count is never equal to 100 (sure, at some point it'll be greater than 100, but your while loop doesn't check for this condition) and the while loop goes on and on.

What you want is probably:

while count < 100: # Or <=, if you feel like printing a hundred. 

Not:

while count != 0:  # Spaces around !=. Makes Guido van Rossum happy. 

Now the loop will terminate when count >= 100.

Take a look at Python documentation.