language

<?php
//变量以$开始
//&引用变量
$a=5;
$b=&$a;
echo "b:$B";
$a=3;
echo "b:$b";
$b =7;
echo "a:$a";
//可变变量
$aa="hello";
$$aa="wold!";
echo $hello.$aa.$$aa;//wold!hellowold!
function test()
{
    static $count = 0;//添加static静态声音用来保存函数运行变量结束递归用，否则无限循环$count=1

    $count++;
    echo $count."&nbsp";
    if ($count < 10) {
        test();
    }
    $count--;//递归结束后运行
    echo "&nbsp.".$count;
}
test();//1 2 3 4 5 6 7 8 9 10  .9 .8 .7 .6 .5 .4 .3 .2 .1 .0
//echo $count;
//常量大小字敏感，可以用define(),php5.3.0后可以用const定义
define("CONSTANT","hello word.");
echo CONSTANT;
const CONSTANT1 = 'Hello World';//php5.3.0以下syntax error
echo CONSTANT1;
/*魔术常量LINE FILE DIR FUNCTION CLASS TRAIT METHOD NAMESPACE
https://www.php.net/manual/zh/language.constants.predefined.php*/
?>

 

https://www.php.net/manual/zh/language.variables.php