True while loop python

Question

I've been trying to understand this for a while now and I don't get why the true while loop doesn't exit when the check() function returns False value and asks input(i.e "enter input")again and again but it exits when else statement of func() function returns False value. No matter what,as far as I know, the while loop should stop or exit when the value returned is false, but that isn't the case here. I don't intend to modify the code but would just like to understand the concept behind this. please help me. Thanks! in advance.

def check(num):
 if(num%2==0):
 return True
 else:
 return False
def func():
 temp=[str(i) for i in range(1,51)]
 while True:
 c=input("enter input: ")
 if c in temp:
 c=int(c)
 if check(c):
 print(c)
 break
 else:
 print("input invalid, enter only digits from 1 to 50")
 return False

• Robin Zigmond: Your code doesn't have any return statement, or other way to end the loop, when the if c in temp condition passes but the if check(c) one doesn't. Try following the logic yourself, step by step, if this is unclear
• Péter Leéh: Note that your check function can just return num % 2 == 0 .

Answer 1

It would most likely be due to the fact that the while true loop being used in the func() function is local to that function and so when you try to use the other function check() to actually change the value, it cannot do so. It would only be able to return false or true for a while loop that is included in the same function.

Answer 2

To exit a loop (for or while) outside a function or exit within the funtion but only exiting the loop you should use break instead of return.

Answer 3

The blank return that you have doesn't actually do anything.

You will have to break from the loop.

It works in the second case as you actually return a value like False

Answer 4

You could try doing this:

loop = True
def check(num):
 global loop
 if(num%2==0):
 loop = False
 else:
 loop = False
def func():
 global loop
 temp=[str(i) for i in range(1,51)]
 while loop:
 c=input("enter input: ")
 if c in temp:
 c=int(c)
 if check(c):
 print(c)
 loop = False 
 else:
 print("input invalid, enter only digits from 1 to 50")
 loop = False

• TechBee: thank you! but i actually don't intend to exit the loop, i just want to understand the concept behind why does the loop exit when func() function returns false value and doesn't exit when the same false value is returned by check() function.