PHP Cookies
cookie 常用于识别用户。
什么是 Cookie？
cookie 常用于识别用户。cookie 是服务器留在用户计算机中的小文件。每当相同的计算机通过浏览器请求页面时，它同时会发送 cookie。通过 PHP，您能够创建并取回 cookie 的值。
如何创建 cookie？
setcookie() 函数用于设置 cookie。
注释：setcookie() 函数必须位于 标签之前。
语法setcookie(name, value, expire, path, domain);
在下面的例子中，我们将创建名为 "user" 的 cookie，把为它赋值 "Alex Porter"。我们也规定了此 cookie 在一小时后过期：
<?phpsetcookie("user", "Alex Porter", time()+3600);?><html><body></body></html>注释：在发送 cookie 时，cookie 的值会自动进行 URL 编码，在取回时进行自动解码（为防止 URL 编码，请使用 setrawcookie() 取而代之）。
如何取回 Cookie 的值？
PHP 的 $_COOKIE 变量用于取回 cookie 的值。
在下面的例子中，我们取回了名为 "user" 的 cookie 的值，并把它显示在了页面上：
<?php// Print a cookieecho $_COOKIE["user"];// A way to view all cookiesprint_r($_COOKIE);?>
在下面的例子中，我们使用 isset() 函数来确认是否已设置了 cookie：
<html><body><?phpif (isset($_COOKIE["user"]))echo "Welcome " . $_COOKIE["user"] . "!<br />";elseecho "Welcome guest!<br />";?></body></html>
如何删除 cookie？
当删除 cookie 时，您应当使过期日期变更为过去的时间点。
删除的例子：
<?php// set the expiration date to one hour agosetcookie("user", "", time()-3600);?>如果浏览器不支持 cookie 该怎么办？
如果您的应用程序涉及不支持 cookie 的浏览器，您就不得不采取其他方法在应用程序中从一张页面向另一张页面传递信息。一种方式是从表单传递数据（有关表单和用户输入的内容，稍早前我们已经在本教程中介绍过了）。
下面的表单在用户单击提交按钮时向 "welcome.php" 提交了用户输入：
<html><body><form action="welcome.php" method="post">Name: <input type="text" name="name" />Age: <input type="text" name="age" /><input type="submit" /></form></body></html>
取回 "welcome.php" 中的值，就像这样：
<html><body>Welcome <?php echo $_POST["name"]; ?>.<br />You are <?php echo $_POST["age"]; ?> years old.</body></html>
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