Definition of functions in php

A function is to encapsulate a piece of code that is used to complete a specific function. A popular understanding of a function: a block of code that can complete a certain task, just like the building blocks used by children to build a house. It can be used repeatedly. When used, it can be used immediately without considering its internal structure. Below we will introduce to you the definition and use of php functions.

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##Custom function

The definition of a function consists of the following four parts:

Keyword function

Function name functionName

Parameter

Function body

	function 函数名([参数1, 参数2, ……]){
	    函数体……
	}

Description of each part

Function: Keywords that must be used when declaring a function

Function name: An identifier that must conform to PHP, and the function name is unique , not case sensitive

[Parameter 1, Parameter 2...]: The value passed to the function from the outside world, it is optional, use commas "," to separate multiple parameters.

Function body: The main body of the function definition, a code segment specifically used to implement a specific function.

Return value: You need to use the return keyword to pass the data to be returned to the caller.

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