在函数中执行python变量

Question

I'm trying to execute a variable called id_choice after it was called in a function I defined called movie_choice .

This is how the function looks like:

def movie_choice():  
    user_input = raw_input("Would you like to serch your movie by IMDB ID or by\ title? ").upper()
if user_input == "ID":
    id_choice = raw_input("Enter imdb ID: ")
    print("Serching . . .")
    return id_choice
elif user_input == "TITLE":
    title = raw_input("Enter movie title: ")
    print("Serching . . .")
    return title
elif user_input == "EXIT":
    sys.exit
else:
    print("Please enter a valid choice. ")
    return movie_choice()

api_key = '1234'
url = "http://www.omdbapi.com/?%s&%s" % (id_choice, api_key)
print (url)

After I defined this function, for example if I'll try to print (id_choice) I will get an error because id_choice is not defined. How can I solve this problem?

I'm new to coding so I'm sorry if the answer to my question will be obvious to some of you. Thanks and appreciate the help!

Answer 1

If you want to call 'id_choice' on the outside of your function,

You need to define it ... on the OUTSIDE of your function

This concept is known as scope . Read up on it. Since the variable, 'id_choice', is defined within the 'movie_choice' function, you can only access it within that function. In the code below, I've defined it before the 'movie_choice' function. Your code should work now.

Also make sure you are indenting correctly. Those if statements should be indented to the inside of your function:

id_choice = ''

def movie_choice(): 
    title = '' 
    user_input = raw_input("Would you like to serch your movie by IMDB ID or by\ title? ").upper()

    if user_input == "ID":
        id_choice = raw_input("Enter imdb ID: ")
        print("Serching . . .")
        return id_choice
    elif user_input == "TITLE":
        title = raw_input("Enter movie title: ")
        print("Serching . . .")
        return title
    elif user_input == "EXIT":
        sys.exit
    else:
        print("Please enter a valid choice. ")
        return movie_choice()

api_key = '1234'
url = "http://www.omdbapi.com/?%s&%s" % (id_choice, api_key)
print (url)

Additionally, you need to define your other variables OUTSIDE your if statements.

If there's a possibility that id_choice is never going to be defined, then you cannot possibly try to print a variable that is not defined. But by defining it on the outside of your conditionals (or function), you are ensuring that those variables will always have a default value.

At the moment, your url has the chance of being incorrect because what if the user does not enter "ID" as the user input? Think of restructuring your code paths to meet that case.

In conclusion, read up on scope and identation .

Answer 2

kay is right about needing to assign variables in the scope where you are accessing them but that is not the problem here . If I understand correctly I just think your indentation is off and what you really want this:

def movie_choice():  
    user_input = raw_input("Would you like to serch your movie by IMDB ID or by\ title? ").upper()
    if user_input == "ID":
        id_choice = raw_input("Enter imdb ID: ")
        print("Serching . . .")
        return id_choice
    elif user_input == "TITLE":
        title = raw_input("Enter movie title: ")
        print("Serching . . .")
        return title
    elif user_input == "EXIT":
        sys.exit
    else:
        print("Please enter a valid choice. ")
        return movie_choice()

movie_selection = movie_choice()
print(movie_selection)

Note: Bear in mind that this method is still not very good because like abarnert said, not all code paths lead to a proper return value ( user_input of EXIT just leads to exiting the program.)

Hope this helps.