Python函数定义全局参数

Question

Can someone explain why the gloabl variable x & y are not recognized in printfunc,

code.py

global x
global y

def test(val_x=None,val_y=None)
    x = val_x
    y = val_y
    printfunc()

def printfunc():
   print('x',x)
   print('y',y)

if __name__ = '__main__':
   test(val_x=1,val_y=2)

Answer 1

place the global inside test() .

global is used inside functions so that we can change global variables or create variables that are added to the global namespace. :

   def test(val_x=None,val_y=None):
        global x
        global y
        x = val_x
        y = val_y
        printfunc()

Answer 2

The global keyword is used inside code block to specify, that declared variables are global, not local. So move global inside your functions

def test(val_x=None,val_y=None): #you also forgot ':' here
  global x, y
  x = val_x
  y = val_y
  printfunc()

def printfunc():
  global x, y
  print('x',x)
  print('y',y)