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Teacher's comments：完成的不错，继续努力
Collection
Collection
`
<!--//2、POST 请求-->
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport"
content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>POST 请求</title>
</head>
<body>
<form action="" method="post">
<label for="email">邮箱：</label>
<input type="email" id="email" name="email" value="<?php echo isset($_POST['email'] ) ? $_POST['email'] : ''; ?>">
<label for="password">密码：</label>
<input type="password" id="password" name="password" value="<?php echo $_POST['password'] ? $_POST['password'] : '';?>">
<button>登录</button>
</form>
</body>
</html>
<?php
echo $_POST[‘email’];
echo ‘<br>‘;
echo $_POST[‘password’];
echo ‘<br>‘;
// 获取变量之前要进行判断,用isset()
//if (isset($_POST[‘password’])) {
// echo $_POST[‘password’];
//} else { // 给个默认值
// echo ‘空’;
//}
if (empty($_POST[‘password’])) {
echo ‘null’;
} else { // 给个默认值
echo $_POST['password'];
}
echo ‘<hr>‘;
echo ‘<pre>‘;
print_r($_POST);`
`<?php
//strtolower() 将字符串转化为小写
$str = ‘ASDFG’;
$str =strtolower($str);
echo $str;
echo ‘<hr>‘;
//strtoupper 将字符串转化为大写
$str = strtoupper($str);
echo $str;
echo ‘<hr>‘;
//strlen() 获取字符串长度
echo strlen($str);
echo ‘<hr>‘;
//str_replace() 字符串替换
$a= str_replace(‘AS’,’GXG’,$str);
echo $a;
echo ‘<hr>‘;
//9、md5()
$str = ‘123456’;
echo md5($str);
echo ‘<hr>‘;
//count() 数组中元素的数量
$arr = array(
‘欧阳克’,
‘黄蓉’,
‘郭靖’
);
echo count($arr);
echo ‘<hr>‘;
//2、array_merge()
$arr1 = array(
‘欧阳克’,
‘黄蓉’
);
$arr2 = array(
‘郭靖’,
‘杨康’
);
$arr3 = array_merge($arr1,$arr2);
print_r($arr3);
echo ‘<hr>‘;
`