Python: Use of function variables

1. The upper function cannot directly use the variables of its nested function;

def func1 (x, y):     = x + y    def  Func2 ():        = 3    + =    mreturn  Zprint (Func1 (1, 2))#  error: Name ' m ' is not defined

2. Variables in the upper function can be used directly within their nested functions:

def func1 (x, y):     = x + y    def  Func2 ():        = 3 + z        return  m      return  func2 ()print(func1 (1, 2))#  output: 6

3. In nested functions, the upper function variable cannot be used, and its own variable has the same name as the upper layer variable:

def func1 (x, y):     = x + y    def  Func2 ():        # m=3 + z:z is the upper function variable        m = 3 + z          # z=m * * 2:z is a variable of the FUNC2 () function itself        z = m * * 2        return     zreturn  Func2 ()print(func1 (1, 2))#  error: local variable ' z ' referenced before assignment 

# declare the variable in advance to be a non-local variable (the system automatically looks for the variable from the upper function): nonlocal Z

# Variables in code z are all variables of the func1 () function

• def func1 (x, y):     = x + y    def  Func2 ():        nonlocal z        = 3 + z        + = m         return Z     return Func2 () Print (Func1 (1, 2)) # Output: 9

4. The formal parameter of the upper function (x, y) can be used directly in its nested function;

def func1 (x, y):     def Func2 ():         = 3 + x        = m + y        return  z    return  func2 () Print (Func1 (1, 2)) # Output: 6

5. The formal parameter of the upper function (x, y) can be the formal parameter of its nested function: The name of the formal parameter must be the same

def func1 (x, y):     def Func2 (x, y):         = 3 + x        = m + y        return  z    return  func2 (x, y) C15>print(func1 (1, 2))#  output: 6

Python: Use of function variables