Python: Program running fine but skipping over output lines in code-CodePudding

When I run the following code:

def collatz(number):
   if number % 2 == 0:
       return number // 2
       result = number
       print(number)
   elif number % 2 == 1:
       return 3 * number   1
       result = number
       print(number)


n = input('Enter a number: ')
while n != 1:
   n = collatz(int(n))

the code runs to get the number to 1, but it always seems to skip the lines

result = number
print(number)

because it does not show any output. But when I visualize it, it is running the number to one. Could someone help explain why that is happening? Thanks so much.

CodePudding user response：

You are using a recursive loop that bypasses those two statements.

def collatz(number):
   if number % 2 == 0:
       return number // 2 <---- exits function here
       result = number
       print(number)
   elif number % 2 == 1:
       return 3 * number   1  <---- exits function here
       result = number
       print(number)

The same concept applies if you have the following function.

def add(x,y):
    return x   y
    print(x)

You would never get to the print(x) statement as you are exiting the function before that line of code!

CodePudding user response：

You need to remove the return statement. Return exits the collatz function immediatly.

CodePudding user response：

this is because it returns the value and it doesn't continue after the return, so you could do:

def collatz(number):
   if number % 2 == 0:
       result = number / 2
       print(result)
       return result
   elif number % 2 == 1:
       result = 3 * number   1
       print(result)
       return result


n = input('Enter a number: ')
while n != 1:
   n = collatz(int(n))

CodePudding user response：

When a function sees return it ends immediately and outputs the value after the word. So to get the lines to run, they need to be before the word return:

def collatz(number):
   if number % 2 == 0:
       result = number
       print(number)
       return number // 2
   elif number % 2 == 1:
       result = number
       print(number)
       return 3 * number   1


n = input('Enter a number: ')
while n != 1:
   n = collatz(int(n))