Python – Variable won't print? (Trying to get variable outside of while/if, etc.)

I have this code:

global dir_name
dir_name = ''

def generateDirectoryName(newpath, x=0):
    while True:
        dir_name = (newpath + ('_' + str(x) if x != 0 else '')).strip()
        if not os.path.exists(dir_name):
            os.mkdir(dir_name)
            #1
            #print(dir_name)
            return dir_name
        else:
            x = x + 1


def createDirectory():
    generateDirectoryName(newpath)


def main():
    cwd = os.getcwd()
    createDirectory()

#2
print(dir_name)

main()

#3
print(dir_name)

When I try the code, the two prints at the end (labelled with comments 2 and 3 don’t appear to have any effect. However, if I uncomment the print inside the function (at comment 1), it will show the dir_name value. Why does this happen – why can’t I access dir_name outside the function? How can I fix the problem?

>Solution :

dir_name is a local variable in your function. In order to change it to global you have to use global dir_name inside the function. As far as printing goes, dir_name is actually getting printed at 2 and 3 but is just an empty string. Also, you dont have to return dir_name as you’re not assigning the return value of generateDirectoryName(newpath, x=0) to anything in createDirectory. Here is an updated version of your code:

dir_name = ''

def generateDirectoryName(newpath, x=0):
    global dir_name
    while True:
        dir_name = (newpath + ('_' + str(x) if x != 0 else '')).strip()
        if not os.path.exists(dir_name):
            os.mkdir(dir_name)
           #1
            #print(dir_name)
            return
        else:
            x = x + 1


def createDirectory():
    generateDirectoryName(newpath)


def main():
    cwd = os.getcwd()
    createDirectory()

#2 (This will still print an empty string)
print(dir_name)

main()

#3 (This will print whatever is printed in #1)
print(dir_name)