从一个函数调用变量到另一个函数的问题

Question

I am trying to call a variable from one function into another by using the command return , without success. This is the example code I have:

def G():
    x = 2
    y = 3
    g = x*y
    return g

def H():
    r = 2*G(g)
    print(r)
    return r
H()

When I run the code i receive the following error NameError: name 'g' is not defined

Thanks in advance!

Answer 1

Your function def G(): returns a variable. Therefore, when you call it, you assign a new variable for the returned variable.

Therefore you could use the following code:

def H():
    G = G()
    r = 2*G
    print (r)

You don't need to give this statement:

return r

Answer 2

While you've accepted the answer above, I'd like to take the time to help you learn and clean up your code.

NameError: name 'g' is not defined

You're getting this error because g is a local variable of the function G()

Clean Version:

def multiple_two_numbers():
    """
      Multiplies two numbers

      Args:
        none

      Returns:
        product : the result of multiplying two numbers
    """

    x = 2
    y = 3
    product = x*y
    return product


def main():

    result = multiple_two_numbers()
    answer = 2 * result
    print(answer)

if __name__ == "__main__":
    # execute only if run as a script
    main()

Problems with your code:

1. Have clear variable and method names. g and G can be quiet confusing to the reader.

2. Your not using the if __name__ == "__main__":

3. Your return in H() unnecessary as well as the H() function.

4. Use docstrings to help make your code more readable.

Questions from the comments :

I have one question what if I had two or more variables in the first function but I only want to call one of them

Your function can have as many variables as you want. If you want to return more than one variable you can use a dictionary(key,value) List, or Tuple. It all depends on your requirements.

Is it necessary to give different names, a and b , to the new variables or can I use the same x and g ?

Absolutely! Declaring another variable called x or y will cause the previous declaration to be overwritten. This could make it hard to debug and you and readers of your code will be frustrated.