1. Strings can be inside the character can be accessed like an array, such as $s = "123", $s [1] is equal to 2, if the string is Chinese will be garbled, need to use MB_SUBSTR to intercept;
The single quotation mark in 2.php ("") is not required to compile the interpretation of the direct output, double quotation marks ("") is required to be compiled to interpret, and then output, so single quotation marks than double quotes output faster, two double quotation marks can be directly written in the variable;
3.mysql_close the default is to close the last open connection, although the DLL has not been extended, or recorded;
The 4.STRRCHR () function finds the last occurrence of a string in another string and returns all characters from that position to the end of the string.
5.session also provides a function session_set_cookie_params (), to set the lifetime of the session, the function must be called before the session_start () function call ;