php学习笔记
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>php学习笔记</title>
<style>
<!--修改css-->
body {background-color:black; color:white;}
h1{font: 72pt arial bold;}
</style>
</head>
<body>
<?php
//注释
#注释
/*
* 注释
*/
$a = 5;
$b = 010; //八进制
$c = 0xf;
echo '$b=' . "$b<br>";
print '$c=' . "$c<br>";
echo '$a<br>'; //单引号对引号里不识别
print '$a<br>';
//转义字符\n换行并归零 \br换行 \t \' \" \$ \r回车(这里的换行符是显示在源代码里面的换行符，在网页里并不会显示)
//null 1)被赋值null 2)尚未被赋值 3)被unset
$var = 1.1;
echo "$var is a " . gettype($var) . "<br>"; //.用于连接字符串,输出1.1 is a double
var_dump($var); //输出变量类型，这里是:float
//转换变量类型->自动由小到大
//强制转换 cast或settype();
echo "<br><br>";
//$_SERVER组的内变量
echo "目前执行的文件名称" . $_SERVER['PHP_SELF'] . "<br>";
echo "服务器名" . $_SERVER['SERVER_NAME'] . "<br>";
echo "服务器软件" . $_SERVER['SERVER_SOFTWARE'] . "<br>";
echo "文档的根目录" . $_SERVER['DOCUMENT_ROOT'] . "<br>";
echo "用户相关信息" . $_SERVER['HTTP_USER_AGENT'] . "<br>";
echo "远程用户的地址" . $_SERVER['REMOTE_ADDR'] . "<br>";
echo "远程用户的连接端口" . $_SERVER['REMOTE_PORT'] . "<br>";
include "GetIP.php";
GetIP();
//常量
echo "你的系统是：" . PHP_OS . "<br>";
echo "目前使用的PHP版本是：" . PHP_VERSION . "<P>";
//自定义常量
define("PI", 3.14159);
echo PI . "<br>";
//运算符同c，注意.是连接字符串运算符
//位运算符同；逻辑运算符：^按位异或...
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