Function creation and call in Python

One 、 Preface

Two 、 Create a function

3、 ... and 、 Call function

Four 、pass Empty statement

Mention functions , You can think of mathematical functions , Function is the most important module in Mathematics , Throughout the whole mathematics learning , stay Python in , Functions are widely used . We've touched on functions many times before . for example , For output print() function 、 For input input() function , And... For generating a series of integers range() function . These are all Python Built in standard functions , You can use it directly . In addition to the standard functions that can be used directly ,Python Custom functions are also supported . That is, by changing a regular 、 Duplicate code defined as a function , To achieve the purpose of writing multiple calls at one time . Using functions can improve code reuse .

Creating a function is also called defining a function , It can be understood as creating a tool with a certain purpose .

Use def Keyword implementation , The specific syntax format is as follows ：

Parameter description ：

functionname： The name of the function , Use when calling a function

parameterlist： Optional parameters , Used to specify parameters passed to a function , If you have more than one parameter , Use commas between parameters “,” Separate ; If you don't specify , It means that the function has no parameters . In the call , No parameters are specified .

comments： Optional parameters , Specifying comments for functions , Comments usually describe the function of the function 、 The function of parameters to be passed, etc .

example ： Define one according to height 、 Weight calculation BMI Exponential function fun_bmi(), This function includes 3 Parameters , Used to specify names respectively 、 Height and weight , According to the formula ：BMI= weight /（ height * height ） Calculation BMI Index , And output the result ,

The code is as follows ：

Run the above code , Nothing will be displayed , It doesn't throw an exception , because fun_bmi() The function has not yet called .

Call function, that is, execute function . If the function created is understood as creating a tool with a specific purpose , Calling a function is equivalent to using the tool . The basic syntax format for calling a function is as follows ：

Parameter description ：

functionname： The name of the function , Use when calling a function

parametersvalue: Optional parameters , Values used to specify individual parameters . If more than one parameter value needs to be passed , Then a comma is used between the two parameter values “,” Separate ; If the function has no arguments , Write a pair of parentheses directly .

example ： Call the above to create fum_bmi function , You can use the following code ：

Running results , As shown below ：

stay Python There is one of them. pass sentence , Represents an empty statement , It doesn't do anything , It usually acts as a placeholder . for example , Create a function , But we don't know what the function is going to do for the time being , It can be used at this time pass Statement fills the body of the function , Express “ I'll fill it in later ”,

The sample code is as follows ：

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