基础部分
声明变量、块级作用域
...
<body>
<?php
if (isset($a)) {
echo "我声明了";
} else {
echo "我没声明"; // true
}
$a = 50;
echo $a; // 50
function test()
{
global $a;
echo $a; // 不加上面那行会报错
}
test();
?>
</body>
...
引入文件
./index.php
<?php
//require_once "./global.php";
include_once "./global.php";
echo $GLOBALS["hello"]; // hello php
?>
···
./global.php
<?php
$GLOBALS["hello"]="hello php";
?>
include 的文件中出错了，主程序继续往下执行，require 的文件出错了，主程序也停了，所以包含的文件出错对系统影响不大的话（如界面文件）就用 include，否则用 require。
数组
$arr = array('0' => "苹果", '1' => "测试");
echo $arr[0]; // 苹果
session 会话机制
./index.php
session_start();
$_SESSION['views']=1;
···
./a.php
session_start();
$_SESSION['views']=1;
echo $_SESSION['views']; // 1
表单请求
./index.php
<form action="./a.php" method="get">
用户名：<input type="text" name="username">
密码：<input type="password" name="password">
<input type="submit" value="提交">
</form>
···
<?php
header("Content-type:text/html;charset=utf-8");
$username = $_GET['username'];
//$username = $_REQUEST['username'];
//$username = $_POST['username'];
if ($username == "admin") {
echo $_GET['password'];
} else {
echo '不是admin';
}
?>
ajax 请求
./index.php
用户名：<input type="text" id="username" >
密码：<input type="password" id="password" >
<input id="btn" type="submit" value="提交">
<script src="https://cdn.bootcss.com/jquery/3.4.1/jquery.js"></script>
<script>
$("#btn").click((ev) => {
ev.preventDefault();
$.ajax({
url: "a.php",
type: "get",
dataType: "json",
data: {
username: $('#username').val(),
password: $('#password').val(),
},
success: data => {
console.log(data);
},
error: err => {
console.log(err);
}
})
});
</script>
...
./a.php
<?php
$username = $_GET['username'];
//$username = $_REQUEST['username'];
//$username = $_POST['username'];
if ($username == "admin") {
echo json_encode(array('msg' => '登陆成功', 'errCode' => 'yes'),JSON_UNESCAPED_UNICODE);
} else {
echo json_encode(array('msg' => '登陆失败', 'errCode' => 'no'),JSON_UNESCAPED_UNICODE);
}
?>
