blankyao 说“学习的过程就是不断的发现错误，不断的改正错误”；
先看下手册上怎么说的吧！
对一般人来说看下前两段就可以了
Magic Quotes
代码:
Magic Quotes is a process that automagically escapes incoming data to the PHP script. It's preferred to code with magic quotes off and to instead escape the data at runtime, as needed.
What are Magic Quotes
代码:
When on, all ' (single-quote), " (double quote), / (backslash) and NULL characters are escaped with a backslash automatically. This is identical to what addslashes() does.
There are three magic quote directives:
magic_quotes_gpc
代码:
Affects HTTP Request data (GET, POST, and COOKIE). Cannot be set at runtime, and defaults to on in PHP.
magic_quotes_runtime
代码:
If enabled, most functions that return data from an external source, including databases and text files, will have quotes escaped with a backslash. Can be set at runtime, and defaults to off in PHP.
magic_quotes_sybase
代码:
If enabled, a single-quote is escaped with a single-quote instead of a backslash. If on, it completely overrides magic_quotes_gpc. Having both directives enabled means only single quotes are escaped as ''. Double quotes, backslashes and NULL's will remain untouched and unescaped.
Why use Magic Quotes
１ Useful for beginners
Magic quotes are implemented in PHP to help code written by beginners from being dangerous. Although SQL Injection is still possible with magic quotes on, the risk is reduced.
２Convenience
For inserting data into a database, magic quotes essentially runs addslashes() on all Get, Post, and Cookie data, and does so automagically.
Why not to use Magic Quotes
１ Portability
代码:
Assuming it to be on, or off, affects portability. Use get_magic_quotes_gpc() to check for this, and code accordingly.
２ Performance
代码:
Because not every piece of escaped data is inserted into a database, there is a performance loss for escaping all this data. Simply calling on the escaping functions (like addslashes()) at runtime is more efficient.
Although php.ini-dist enables these directives by default, php.ini-recommended disables it. This recommendation is mainly due to performance reasons.
３ Inconvenience
代码:
Because not all data needs escaping, it's often annoying to see escaped data where it shouldn't be. For example, emailing from a form, and seeing a bunch of /' within the email. To fix, this may require excessive use of stripslashes().
这些英文实在是需要像我这类人有足够的耐心啊（不是说我有耐心，而是我英语烂），刚才也说了，对于一般人只看下前两段就可以了，特别是我用红色标出来的字！！！
另外，特别注意的是，魔术引用发生作用是在传递$_GET,$_POST,$_COOKIE时
下面是案例
