It is a good explanation of the difference between addslashes and mysql_real_escape_string. Although many domestic PHP coders still rely on addslashes to prevent SQL injection (including me), I still recommend that everyone strengthen checks to prevent SQL injection in Chinese. The problem with addslashes is that hackers can use 0xbf27 to replace single quotes, while addslashes only changes 0xbf27 to 0xbf5c27, which becomes a valid multi-byte character. 0xbf5c is still regarded as a single quote, so addslashes cannot successfully intercept.
Of course, addslashes is not useless. It is used for processing single-byte strings. For multi-byte characters, use mysql_real_escape_string.
In addition, for the example of get_magic_quotes_gpc in the PHP manual:
Copy the code The code is as follows:
if (!get_magic_quotes_gpc()) {
$lastname = addslashes($_POST['lastname']);
} else {
$lastname = $_POST['lastname'];
}
It is best to check $_POST['lastname'] when magic_quotes_gpc is already open.
Let’s talk about the difference between the two functions mysql_real_escape_string and mysql_escape_string:
mysql_real_escape_string must be used under (PHP 4 >= 4.3.0, PHP 5). Otherwise, you can only use mysql_escape_string. The difference between the two is:
mysql_real_escape_string takes into account the current character set of the connection, while mysql_escape_string does not.
To summarize:
addslashes() is a forced addition;
mysql_real_escape_string() will determine the character set, but there are requirements for the PHP version;
mysql_escape_string does not consider the current character set of the connection.
The above introduces stripslashes php addslashes and mysql_real_escape_string, including the content of stripslashes. I hope it will be helpful to friends who are interested in PHP tutorials.

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The session realizes user authentication through the server-side state management mechanism. 1) Session creation and generation of unique IDs, 2) IDs are passed through cookies, 3) Server stores and accesses session data through IDs, 4) User authentication and status management are realized, improving application security and user experience.

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Methods to debug session problems in PHP include: 1. Check whether the session is started correctly; 2. Verify the delivery of the session ID; 3. Check the storage and reading of session data; 4. Check the server configuration. By outputting session ID and data, viewing session file content, etc., you can effectively diagnose and solve session-related problems.

Multiple calls to session_start() will result in warning messages and possible data overwrites. 1) PHP will issue a warning, prompting that the session has been started. 2) It may cause unexpected overwriting of session data. 3) Use session_status() to check the session status to avoid repeated calls.

Configuring the session lifecycle in PHP can be achieved by setting session.gc_maxlifetime and session.cookie_lifetime. 1) session.gc_maxlifetime controls the survival time of server-side session data, 2) session.cookie_lifetime controls the life cycle of client cookies. When set to 0, the cookie expires when the browser is closed.


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