Python Basics (Functions)

Why use functions?     
   Solve the problem of code reuse 
    Unified maintenance The organization structure of the program is clear and the
     readability 
is
 strong The form of 
an empty function 

function:
 def function name (arg1, arg2, arg3): #arg parameter optional 
    'description information' 
    function body 
    return 0 #return value 

definition parameterized function
 def bar(x,y): with parameters in parentheses Called the parameterized function 
    print(x) The parameters of the 
    print(y) 

function: 
def foo(x,y): #Formal parameters: in the function definition stage, the parameters defined in parentheses 
foo (1, 2) #Actual parameters: in In the function call phase, the parameters defined in parentheses are 
analyzed from the perspective of actual parameters: 
1. Pass the value by position eg: foo(1,2)

2. Pass the value by keyword eg:foo(x=1,y=2)

3. Mixed use of positional value and keyword value (note: positional value must be in front of keyword value; only one value can be assigned to a formal parameter) eg: foo(1,y=2)

Analysis from the perspective of formal parameters: positional parameters must be passed by value. Default parameters must be placed after positional parameters 
def foo(*args): 
def foo(x,*args,y=1):*args should be placed after positional parameters* args returns a tuple in the form 
def foo(x,**kwargs): **kwargs returns a dictionary in the form 
def foo(x,*args,**kwargs): 

defines a parameterless function
 def foo() : 
    'foo function' 
    print('from the foo') 
print(foo.__doc__) 

defines an empty function 
def auth(): 


The calling statement of the     pass function is in the form of: foo() #There are no parameters in the definition and no parameters in the call           bar(1 ,2) #There are parameters in the definition, and the parameters need to be passed when calling. The expression is in the form: res=10*my_sum(1,2) The function call is used as a parameter of another function: print(my_sum(1,2)) def function(x ,y): # Ternary operator     res=x if x > y else y     return res hehe = function (1, 2) print (hehe) The return value of the function can be any type without return--->None













return 1--->1 returns this value 
return 1,2,3--->(1,2,3) returns a tuple