Code:
<?php
foreach($_POST as $key=>$val){
echo $key."==>".$val."<br>";
}
echo $_GET["username"]."<br>";
echo $_GET["password"]."<br>";
print_r($_POST);
echo "post<br>";
print_r($_GET);
echo "get<br>";
print_r($_REQUEST);
echo "request<br>";
?>
<form actiion="demo.php" method="post">
username: <input type="text" name="username"><br>
password: <input type="password" name="password"><br>
<input type="submit" value="login">
</form>
不建议使用$_REQUEST.