Function parameters (positional parameters, default value parameters, variable parameters, named keyword parameters, keyword parameters)

Positional arguments ：

                 Argument and formal parameter positions , One-to-one correspondence
Default parameter ：

                 Set the default value for a parameter of the formal parameter , If this parameter does not pass in the corresponding value , Calculate by default , If the corresponding value is passed in , Calculate according to the value passed in

                

               ※  The default value parameter is written later

               ※  Formal parameters are not necessary   Don't point to a mutable object （ Such as ,list、set、tuple）
               ※  So avoid the above situation , The default value parameter must point to an immutable object （ Such as ,None）

                

Variable parameters ： *  Variable name （ It could be a variable , List name 、 Tuple name ）

                    Pass in 0 Two or more parameters , Encapsulate the parameters into Tuples
                   * Represents a variable parameter   

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Key parameters ： **  Variable name

                      Pass in 0 Two or more parameters , Encapsulate the parameters into Dictionaries
                      ** Represents a variable parameter

 

​​​​​​​ Named key parameters ：

person(" Zhang San ",19," Beijing "," male ") Error reason ： Is there no named keyword , The system defaults to position parameters ,person(name,age,*,city,gender) The function has only two positional arguments , So there's an error . 

  Add ：

        1. If variable parameters already appear in function parameters （*）,
             You can omit named keywords *（ Because variable parameters can be transferred , Don't pass it on ）

       2. You can set default values for named keyword parameters ​​​​​​​​​​​​​​

 

Parameter combination ：
     Five parameter types can be combined , But there is a certain order （ Positional arguments 、 Default parameter 、 Variable parameters 、 Named key parameters 、 Key parameters ）
 

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