First Python script: number-guessing game with a global variable

This is my first Python script, and I was hoping to get some feedback. I do have one specific question: is the use of global variables considered a bad practice? When I used them below, my programmer's instincts immediately went off as though I was creating a code-smell, mostly because it seems much less elegant than just having a private String myVariable at the top of a Java class. The use of global myVariable to force the scope seemed a bit hacky. But I don't know a single thing about Python except what I wrote below, so I could be way off.

I also realize that the below code is more complex than it needs to be. I know that it could be written in much fewer lines of code by removing function definitions and such (in fact, my first version was only like 15 lines). But I wrote this more complicated version in order to get a handle on some of the basic concepts like sharing variables, returning from functions, etc.

Any tips or glaring style/best-practices issues are appreciated! (I'm a style-Nazi with Java, so please, don't hold back so that I can learn!)

```
#!/usr/bin/python

from random import randint

# GLOBALS
guesses = 0
the_number = 0

def checkGuess(guess):
global the_number

if guess the_number:
print "The number is LOWER."

return False

def isValid(guess):
return len(guess) > 0 and guess.isdigit()

def getInput():
global guesses
input = ""

while not isValid(input):
input = raw_input("(#" + str(guesses) + ") Guess a number: ")
if not isValid(input):
print "Please guess an integer!"

return int(input)

def runGame(min, max):
global guesses
global the_number

the_number = randint(min, max)
guess = 0

print "I'm thinking of a number between " + str(min) + " and " + str(max) + " ..."

while not checkGuess(guess):
guesses = guesses + 1
guess = getInput()

print "YOU WON!"

def printTitle():

Some notes:

-
Mutable global state is a bad programming practice. Instead, pass values as arguments so functions are black boxes that take values (as arguments) and return values. If such a function does not perform any side-effect (print to console, write a file, ...), then it's a "pure function". Try to write pure functions whenever possible.

-
Conditionals: Don't write a fallback (return False) where some branches get and others don't. Non-overlapping conditionals are more clear.

-
Use name_of_variable and name_of_function.

-
Try to use Python 3 whenever possible.

I'd write:

from random import randint
from itertools import count

def is_guess_correct(number, guess):
    if guess == number:
        return True
    elif guess < number:
        print("The number is HIGHER.")
        return False
    else:
        print("The number is LOWER.")
        return False

def is_valid_guess(number_string):
    return number_string.isdigit()

def get_number(guess_iteration):
    while 1:
        number_string = input("({0}) Guess a number: ".format(guess_iteration))
        if is_valid_guess(number_string):
            return int(number_string)
        else:
            print("Please enter a valid integer!")

def run_game(nmin, nmax):
    number = randint(nmin, nmax)
    print("I'm thinking of a number between {0} and {1}...".format(nmin, nmax))

    for guess_iteration in count(1):
        guess = get_number(guess_iteration)
        if is_guess_correct(number, guess):
            print("YOU WON!")
            break

if __name__ == '__main__':
    run_game(1, 100)

StackExchange Code Review Q#30150, answer score: 5