php学习日记(一)

header 应用：在使用header之前一定不能有任何的输出，类似于echo ,print 也不能有html语句。否则会出现，header has been sended 的错误提示
session篇：
简介:

Session support in PHP consists of a way to preserve certain data across subsequent accesses. This enables you to build more customized applications and increase the appeal of your web site.

A visitor accessing your web site is assigned a unique id, the so-called session id. This is either stored in a cookie on the user side or is propagated in the URL.

----------------------------------------------------------------------
session_start() initialize session data,
session_start()creates a session or resumes the current one based on the current session id that's being pasted via a request such as
GET,POST,or a cookie.
//page1.php
session_start();
$_SESSION["login"]="yes";
.
.
.
?>
//page2.php
if($_SESSION["login"]=="yes")
{
}
else
{
}
?>
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注意在使用session时，要注意同header相同的问题（上有描述）
在一些网上下载的源程序中还能发现session_register(..)函数。
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session_register() accepts a variable number of arguments, any of which can be either a string holding the name of a variable or an array consisting of variable names or other arrays. For each name,session_register() registers the global variable with that name in the current session.

session_refister() 的使用依赖于register_globals=on但是自php 4.2.0起，这一选项被默认设置为off.

you'd better use $_SESSION instead of session_register().