php笔记

Fri, 07 Aug 2026 00:00:00 +0000

PHP基本格式

<?php
echo "Hello";
?>

但在CTF中经常不写最后?> php每条语句用;结尾

php变量前面必须有$

$name = "Clairis";
$age = 18;

$a = "hello";
$b = "Clairis";

$a = 123;

$a = 12.03;

$a = true;
$b = false;

$a = array("Clairis","user");
$a = ["Clairis","users"];

# 访问
echo $a[0];

 $name = "Clairis";
 echo $name;

echo "hello","Clairis";

php的字符串拼接不用+而是.

$a = "hello";
$b = "Clairis";
echo $a . $b;

#输出“helloClairis"

if(isset($_GET['name'])){
	echo $_GET['name'];
}

如果GET参数name存在，就输出name的值

if(!isset($_GET['user']){
	exit;
}

如果没有传user参数，直接结束程序

#多个条件
if($a == 1 && $b == 2){
	echo "success";
}

&& 并且 || 或者

$a == $b

弱比较

PHP可能自动转换数据类型比如： “1” == 1 返回true；因为PHP会进行类型转换