Extreme newbie - Python code skipping to the end (syntax issue?)

Question

When I run the following code, it skips to the end and simply prints "Thanks for playing!"

I'm sure it's something super obvious that I've missed, any ideas? I am using Python 2.7.6.

Thanks.

import random

def roll (sides = 6):
    numberRolled = random.randint(1,sides)
    return numberRolled

def main():
    sides = 6
    rolling = True
    while rolling:
        roll_again = raw_input("Press Enter to roll, or Q to quit.")
        if roll_again.lower() != "q":
            numberRolled = roll(sides)
            print ("You rolled a " + numberRolled)

        else:
            rolling = False
print ("Thanks for playing!")

In Python `main()` doesn't have any special meaning, you're supposed to call it yourself. — Ashwini Chaudhary, Jul 18 '16 at 04:00

score 1 · Answer 1 · answered Jul 18 '16 at 04:02

Python in itself has no concept of a main method. When it reads your code, it imports random, defines a method named roll, defines another method named main, then prints "Thanks for playing". It does nothing else, unless you tell it to

If you want to call main(), you'll need to do this yourself. Traditionally (to work with other code that might want to import yours as a module), it would look like this:

import random

def roll():
    ...

def main():
    ...

if __name__ == '__main__':
    main()
    print("Thanks for playing")

That will check if the module name is __main__ (which is true for the main script) and call your main method

Thanks for the clear explanation! – asz Jul 18 '16 at 04:13 — asz, Jul 18 '16 at 04:13

score 0 · Answer 2 · edited May 23 '17 at 12:08

You need to add if __name__ == '__main__:', and call main() from there:

import random

def roll (sides = 6):
    numberRolled = random.randint(1,sides)
    return numberRolled

def main():
    sides = 6
    rolling = True
    while rolling:
        roll_again = raw_input("Press Enter to roll, or Q to quit.")
        if roll_again.lower() != "q":
            numberRolled = roll(sides)
            print ("You rolled a " + numberRolled)

        else:
            rolling = False

if __name__ == '__main__':
    main()
    print ("Thanks for playing!")

For details as to why and how it works, please see:
- what-does-if-name-main-do
- tutorial name == main
- python documentation

Thank you, that's awesome! Appreciate the extra help links. – asz Jul 18 '16 at 04:12 — asz, Jul 18 '16 at 04:12

score 0 · Answer 3 · edited Jul 18 '16 at 04:22

0

You need to run main

if __name__ == "__main__":
        main()

edited Jul 18 '16 at 04:22

mechanical_meat

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answered Jul 18 '16 at 04:18

CountryRabbit

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Extreme newbie - Python code skipping to the end (syntax issue?)

3 Answers3