Cookie
结果碰到一个问题，setcookie设置了Cookie并没有生效，在浏览器端也没有看到。查了一下，原来是setcookie是通过HTTP请求响应的Header来完成的，需要在请求响应内容输出之前执行（就像其他Header设定一样）。
在php.ini中error_reporting = E_ALL的情况下，输出内容之后再setcookie会弹出以下提示：
复制代码 代码如下:
Warning: Cannot modify header information – headers already sent by (output started at C:\xampp\htdocs\b.php:2) in … on line …
但因为当时php.ini设置成了error_reporting = E_ALL & ~E_NOTICE，于是没有任何提示，所以开发的时候还是建议设成error_reporting = E_ALL 方便观察到一些异常情况。
附一个setcookie用法实例
a.php
复制代码 代码如下:
setcookie("page", "a.php");
$page = $_COOKIE["page"] ? $_COOKIE["page"] : "unknown";
echo "From " . $page . "
";
?>
This is a.php. Go to
b.php b.php
复制代码 代码如下:
setcookie("page", "b.php");
$page = isset($_COOKIE["page"]) ? $_COOKIE["page"] : "unknown";
echo "From " . $page . "
";
?>
This is b.php. Go to
a.php
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