Introduction to the custom functions of PHP functions _php Tutorial

In PHP, more than 700 built-in functions are available. PHP functions are divided into user-defined functions and system-built functions. Built-in functions can be used directly, and user-defined functions need to be defined using the keyword function.

Custom functions
function, which can be seen as a separate set of program statements to implement a function. Once we've written a function into a function, we can use it conveniently wherever we need it. Reasonable use of functions, can make our PHP program more concise and easy to read, more scientific.
Grammar

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function function_name (arg1,arg2,......) { function function code }

Creating PHP Functions
A function is a block of code that can be executed at any time when it is needed.

To create a PHP function:
All functions use the keyword "function ()" to start
Named function-the name of the function should indicate its function. The function name begins with a letter or underscore.
Add "{"-the section after the opening curly brace is the code of the function.
inserting function code
Add a "}"-the function ends by closing the curly braces.
Parameters of the function
The function of a parameter is to pass information to a function.
Example

Now, we're going to use this function in our PHP script:

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function Writemyname () { echo "David Yang"; } echo "Hello world! "; echo "My name is"; Writemyname (); echo ". That's right, "; Writemyname (); echo "is my name."; ?> The output of the above code: Hello world! My name is David Yang. That's right, David Yang is my name.

Example:

The code is as follows

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function City_name ($city) { echo "City name is:". $city; } City_name ("Shanghai"); Executes the function, and the result is output "city Name: Shanghai" string ?> You can specify a default value for the parameters of the function so that the parameter defaults are taken when no parameter values are specified. function City_name ($city = "Beijing") { echo "City name is:". $city; } $name = "Shanghai"; City_name (); Execution result is output "city name: Beijing" City_name ($name); Execution result is output "city name: Shanghai" ?>

http://www.bkjia.com/PHPjc/629078.html www.bkjia.com true http://www.bkjia.com/PHPjc/629078.html techarticle in PHP, more than 700 built-in functions are available. PHP functions are divided into user-defined functions and system-built functions. Built-in functions can be used directly, user-defined functions need to be used ...

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