php笔记

1、PHP的三个有用常量：
   DIRECTORY_SEPARATOR  
   PHP_EOL
   PATH_SEPARATOR

2、namespace，php5.3新加的功能，但是php手册上已经有相关内容。在Language Reference->Namespaces节，但是手册上没有注明版本号。

3、在上传swf的时候，要注意xss攻击。

4、One thing to note in comparison with ==

When we make a comparison with == php automaticly converts strings to integers when either side of the comparison is an integer, f.e.:
$value = 0;
if($value == "submit") {
   echo "Let's submit";
}
?>
Above would be succesful, since "submit" is converted to an integer (eq 0) and the equation is would return true; (that's why (1 == "1submit") would also return true)

That's why we should use strcmp or === (checks type also), for string comparisons.

So my conclusion is that when comparing string, you'd better not make use of == (use strmp or === instead). For integer comparisons the == equation can be usefull, since our values will always be casted to an integer (1 == "1" returns true).

5、