Python Basics-Functions

First, the function

1. What is a function

function (functio), the word derives from mathematics, but the concept of "function" in programming is very different from the function in mathematics and can be understood as a set of encodings that implement a particular function. Functions in programming also have many different names in different languages. In basic it is called subroutine (sub-process or subroutine), in Pascal is called procedure (process) and function, in C only function, in Java is called method.

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

2. Features of functions

• Reduce duplicate code
• To make the program extensible
• Make programs easier to maintain

3. Definition and invocation of functions

You can define a function that you want to function, and here are the simple rules:

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

def functionname (parameters):   "Function _ Document String"   function_suite   return [expression]

Defines a function that gives the function a name, specifies the parameters contained in the function, and the code block structure.

function calls directly with the function name plus arguments: "functionname (Parameters)"

4. function return value (returns)

To get the result of the function execution, you can return the result using the return statement

Attention:

• The function stops executing and returns the result as soon as it encounters a return statement, so can also be understood as a return statement that represents the end of the function
• If return is not specified in the function, the return value of this function is None

Python Basics-Functions