Python learns the "fourth" Python function

I. Introduction to Functions

Functions are well-organized, reusable pieces of code that are used to implement a single, or associated function.

Functions can improve the modularity of the application, and the reuse of the code. You already know that Python provides a number of built-in functions, such as print (). But you can also create your own functions, which are called user-defined functions

Benefits of the function:

• Code reuse
• Consistency and ease of maintenance
• Scalability

Second, the definition of function

Definition rules for functions:

• function code block starts with def keyword, followed by function identifier name and parentheses ()
• Any incoming parameters and arguments must be placed in the middle of the parentheses, and the parentheses can be used to define the parameters
• The first line of the function statement can optionally use the document string-for storing function descriptions
• Function contents start with a colon, and indent
• return [expression] ends the function, optionally returning a value to the caller. Return without an expression is equivalent to returning None

Syntax for the function:

　　

def function Name:    function Body

　　

Examples of functions:

Def Print_hello (): "" "    print Hello    : return:" "" "    print (" Hello ")

　　

Third, the return value of the function

Look at the return value of Python based on the example:

Def fun2 ():    msg = "Hello World"    return Msgdef fun3 ():    return 1, 2, 3 AA = fun1 () BB = fun2 () cc = FUN3 () print (AA ) print (BB) print (cc) # output: # none# Hello world# (1, 2, 3)

Summarize:

1. If no return statement is returned in the function, the Python function returns none by default

2. The function returns a value of 0, the function returns none by default, the function returns a value of 1 is, the object is returned, and the number of returned value is greater than 1 o'clock, a tuple is returned;

Iv. parameters of the function

Python learns the "fourth" Python function