如何通过在 python 中声明全局来从另一个 function 调用变量？

Question

func 1

def num1():
    global h
    h=7

func 2

def num2():  
     print(h)

When I call this function:

num2()

Here, it should print the value of h which is globally declared in func 1 . But it is giving NameError why?? Anyone answer me plz..

Answer 1

to access the global variable h through num2() make sure to call num1() before calling num2()

Answer 2

Defining num1 doesn't actually define h . The definition of num1 just says that, when you call num1 , it will assign to the global name h . If h doesn't exist at that time, it will be created. But defining num1 isn't sufficient to create h .

You need to ensure that h exists before num2 is called. You can do that by assigning to h yourself, or calling num1 .

>>> num2()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in num2
NameError: name 'h' is not defined
>>> h = 3
>>> num2()
3
>>> del h
>>> num2()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in num2
NameError: name 'h' is not defined
>>> num1()
>>> num2()
7