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PHP basics: detailed explanation of custom function usage examples
PHP basics: detailed explanation of custom function usage examples
The article mainly introduces the usage of custom functions in the PHP introductory tutorial, and analyzes the creation of custom functions in PHP, return values, parameters, calling methods, and the use of global variables and magic constants in the form of examples. and other related skills
Demo1.php<?php //标准函数，内置函数 echo md5('123456'); echo '<br/>'; echo sha1('123456'); echo '阅谁问君诵，水落清香浮。'; ?>
<?php
//创建函数，不要跟系统的内置函数重名
//函数有个特性，必须调用，才可以执行
//无参数表示()里面是空的，无返回就是函数的程序里没有 return
function functionName(){
echo '我是一个无参数无返回的函数。';
}
functionName();
?><?php
//包含参数无返回值的函数
//一般来说，写好的函数，就不用修改了
//变化的一般是传入进去的参数
function functionArea($radius){
$area = $radius * $radius * pi();
echo '半径为'.$radius.'的面积为：'.$area;
}
//调用
functionArea(10);
?><?php
//包含参数，有返回值
function functionArea($radius) {
$area = $radius * $radius * pi ();
return $area;
}
//调用
//这样子大大提高了函数的灵活性
//functionArea(20); 整体就得到一个值，在内存里。
echo '半径为20的面积为：'.functionArea(20);
?><?php
//包含参数，有返回值
//这个 $radius = 10，这里的10表示这个参数的默认值
//如果调用函数没有给函数传一个参数，那么就启用默认值
function functionArea($radius = 10) {
$area = $radius * $radius * pi ();
return $area;
}
//调用
//这样子大大提高了函数的灵活性
//functionArea(20); 整体就得到一个值，在内存里。
echo '半径为20的面积为：'.functionArea();
?><?php
//写一个函数，这里函数要返回三条数据
function functionInfo($name,$age,$job){
//$userInfo 是个数组
//$userInfo = array($name,$age,$job);
$userInfo[] = $name;
$userInfo[] = $age;
$userInfo[] = $job;
return $userInfo;
}
//调用函数
print_r(functionInfo('网站',19,'程序员'));
// $arr = functionInfo('网站',19,'程序员');
// echo $arr[0];
// list($name,$age,$job) = functionInfo('网站',19,'程序员');
// echo $name.'今年'.$age.'岁了，他还是个'.$job;
?><?php
//之前的传参，都是按值传参
$prices = 50;
$tax = 0.5;
//这个函数没有任何值出来，目前是按值传参
//函数里的变量和函数外变量没有任何关系
function functionPrices(&$prices,&$tax){
//里面的 $prices 这个变量已经是75
$prices = $prices + $prices * $tax;
$tax = $tax * $tax;
echo $prices;//75
echo '<br/>';
echo $tax;//0.25
echo '<br/>';
}
functionPrices($prices,$tax) ;
//引用这个概念，我们目前无法掌握，会在OOP时候，重点讲解
echo $prices;//按值传50，按引用就变成75
echo '<br/>';
echo $tax;
?><?php
//了解全局变量
//可以将 $a 设置成全局变量
$a = 5;
function fa(){
global $a; //将 $a 设置成为全局变量
$a = 2;
}
fa();
echo $a; //2
?><?php
//使用超级全局变量
$GLOBALS['a'] = 5;
function fa(){
$GLOBALS['a'] = 2;
}
fa();
//echo $GLOBALS['a'] ;
print_r($GLOBALS['a'] );
?><?php //这句话把函数给包含进来 include 'library/tool.library.php'; echo functionPi(); ?>
<?php //include() 语句包含并运行指定文件。 // include 'Demo1.php'; // include 'Demo1.php'; //include_once() 语句在脚本执行期间包含并运行指定文件。 //此行为和 include() 语句类似，唯一区别是如果该文件中的代码已经被包含了，则不会再次包含。 // include_once 'Demo1.php'; // include_once 'Demo1.php'; //只包含引用的文件一次 //include 如果不存在，就告诉你两个警告，然后继续执行 //require 如果不存放，就直接报错，然后就停止执行 require 'Demo1.php'; //我们就推荐使用 require // require 'Demo1.php'; // require_once 'Demo1.php'; // require_once 'Demo1.php'; echo '<strong>阅谁问君诵，水落清香浮。</strong>' ?>
<?php
//FILE
//魔法常量 -- 这里的常量说白了就是一个值而已
// $file = FILE ; //C:\AppServ\www\Basic7\Demo12.php
// echo $file;
//所以，一般包含文件的时候，建议采用 FILE 这样速度更快
echo dirname(FILE);//C:\AppServ\www\Basic7
require (dirname(FILE).'\Demo1.php');//C:\AppServ\www\Basic7
echo LINE;
function ffff(){
return FUNCTION;
}
echo '<hr/>';
echo ffff();
?>The above is the detailed content of PHP basics: detailed explanation of custom function usage examples. For more information, please follow other related articles on the PHP Chinese website!
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