Chapter 7 PHP custom function implementation code_PHP tutorial

7.1. Standard functions
There are more than 1,000 standard functions in the standard PHP distribution package. These standard functions are built into the system and can be used directly without the need for users to create them
For example:

Copy code The code is as follows:

echo md5('123456');
echo '
';
echo sha1('123456');
echo '
';
echo pi();
?>

output
e10adc3949ba59abbe56e057f20f883e
7c4a8d09ca3762af61e59520943dc26494f8941b
3.14159265359
7.2． Custom functions
7.2.1 Basic principles of function naming:
1. The function name cannot have the same name as an existing function name.
2. Function names can only contain letters, numbers and underscores.
3. The function name cannot start with a number
7.2.2 Basic usage: declare with function

Copy the code The code is as follows:

//Create function
function funcCountArea($radius)
{
return $radius*$radius*pi();
}
//Use function
$area = funcCountArea(20);
echo $area;
echo '
';
$area2 = funcCountArea(30);
echo $area2;
?>

output
1256.63706144
2827.43338823
7.2.3 Passing parameters by value

Copy the code The code is as follows:

$a = 5;
function funcChange($a)
{
$a = 2 * $a;
}
funcChange ($a);
echo $a;
?>

output
5
7.2 .4 Pass parameters by reference

Copy code The code is as follows:

$a = 5;
function funcChange(&$a)
{
$a = 2 * $a;
}
funcChange ($a);
echo $a;
?> ;

output
10
7.2.5 Function call that returns multiple values ​​

Copy code The code is as follows :

function funcUserInfo($username,$password)
{
$userInfo = array($username,$password);
return $ userInfo;
}
$arr = funcUserInfo('anllin','123456');
print_r($arr);
?>

output
Array ( [0] => anllin [1] => 123456 )
7.2.6 Another function call that returns multiple values ​​(practical: recommended)

Copy code The code is as follows:

function funcUserInfo($username, $password)
{
$userInfo [] = $ username;
$userInfo [] = $password;
return $userInfo;
}
$arr[] = funcUserInfo ( 'Bob', '512655' );
$arr[] = funcUserInfo ( 'John', '458736' );
$arr[] = funcUserInfo ( 'Mark', '925472' );
print_r ( $arr );
?>

output
Array ( [0] => Array ( [0] => Bob [1] => 512655 ) [1] => Array ( [0] => John [ 1] => 458736 ) [2] => Array ( [0] => Mark [1] => 925472 ) )
Note: Function calls are not case-sensitive, but variable names are Upper and lower case.
7.2.7 Understanding scope:
Local variables:
Variables declared inside a function.
Global variables:
Variables declared outside the function.
7.2.8 Convert local variables to global variables

Copy code The code is as follows:

$a = 5;
function funcChangeValue()
{
global $a;
$a = 10;
}
funcChangeValue();
echo $a;
?>

output
10
7.2.9 Use of super global variable $GLOBALR

Copy code The code is as follows:

$GLOBALS['a'] = 5;
function funcChangeValue()
{
$GLOBALS[' a'] = 10;
}
funcChangeValue();
echo $GLOBALS['a'];
?>

Output
10
7.3． File inclusion
7.3.1 Use of Include, you can include the same file multiple times

Copy code The code is as follows:

include 'demo1.php';
include 'demo1.php';
include 'demo1.php';
?>

output
e10adc3949ba59abbe56e057f20f883e
7c4a8d09ca3762af61e59520943dc26494f8941b
3.14159265359
--------------------------------------------------------------------------------
e10adc3949ba59abbe56e057f20f883e
7c4a8d09ca3762af61e59520943dc26494f8941b
3.14159265359
--------------------------------------------------------------------------------
e10adc3949ba59abbe56e057f20f883e
7c4a8d09ca3762af61e59520943dc26494f8941b
3.14159265359
7.3.2 include_once使用上和include没什么区别，但是调用多次只会包含相同的文件一次

复制代码 代码如下:

include_once 'demo1.php';
include_once 'demo1.php';
include_once 'demo1.php';
?>

output
e10adc3949ba59abbe56e057f20f883e
7c4a8d09ca3762af61e59520943dc26494f8941b
3.14159265359
7.3.3 require() 语句包含并运行指定文件。

复制代码 代码如下:

require 'demo1.php';
require 'demo1.php';
require 'demo1.php';
?>

output
e10adc3949ba59abbe56e057f20f883e
7c4a8d09ca3762af61e59520943dc26494f8941b
3.14159265359
--------------------------------------------------------------------------------
e10adc3949ba59abbe56e057f20f883e
7c4a8d09ca3762af61e59520943dc26494f8941b
3.14159265359
--------------------------------------------------------------------------------
e10adc3949ba59abbe56e057f20f883e
7c4a8d09ca3762af61e59520943dc26494f8941b
3.14159265359
7.3.4 require_once() 语句在脚本执行期间包含并运行指定文件.但是不重复包含相同的文件。

复制代码 代码如下:

require_once 'demo1.php';
require_once 'demo1.php';
require_once 'demo1.php';
?>

output
e10adc3949ba59abbe56e057f20f883e
7c4a8d09ca3762af61e59520943dc26494f8941b
3.14159265359s
7.3.5 include与require的区别
Include后面如果还有其他代码，当调用include出错时，后面的代码还会继续执行，但是require则不会。
Include在调用一个不存在的文件时，会给出警告，但是会继续执行后面的代码。

复制代码 代码如下:

include 'demo111.php';
echo('this is demo13.php');
?>

output
Warning: include(demo111.php) [function.include]: failed to open stream: No such file or directory in D:\AppServ\www\Basic7\demo13.php on line 2
Warning: include() [function.include]: Failed opening 'demo111.php' for inclusion (include_path='.;C:\php5\pear') in D:\AppServ\www\Basic7\demo13.php on line 2
this is demo13.php
Require在调用一个不存在的文件时，会给出一个错误，并中止代码的执行。

复制代码 代码如下:

require 'demo111.php';
echo('this is demo14.php');
?>

Output
Warning: require(demo111.php) [function.require]: failed to open stream: No such file or directory in D:\AppServ\www\Basic7\demo14.php on line 2
Fatal error: require() [function.require]: Failed opening required 'demo111.php' (include_path='.;C:\php5\pear') in D:\AppServ\www\Basic7\demo14.php on line 2
7.4．魔法常量

名称	描述
_FILE_	当前文件名
_LINE_	当前行号
_FUNCTION_	当前函数名
_CLASS_	当前类名
_METHOD_	当前方法名

The so-called magic constant is not a real constant, but a variable that obtains a fixed value according to the occasion

Copy the code The code is as follows:

echo __FILE__;
echo '
';
echo __LINE__;
echo '
';
function funcTest()
{
echo __FUNCTION__;
}
funcTest();
?>

output
D:AppServwwwBasic7demo15.php
5
funcTest

http://www.bkjia.com/PHPjc/324799.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/324799.htmlTechArticle7.1. Standard functions There are more than 1,000 standard functions in the standard PHP distribution package. These standard functions are built into the system and can be used directly without the need for users to create them. For example: Copy the code as follows...