Various encoding settings for php pages_PHP tutorial

PHP’s header() function is used to define the encoding of a PHP page (note: there cannot be any output in front, otherwise an error will be reported)

The PHP page is utf8 encoded: header("Content-type: text/html; charset=UTF-8");

The php page is gbk encoded: header("Content-type: text/html; charset=GBK");

The difference between using header or meta to encode PHP pages

1. Page encoding

　1. Use tag to set page encoding

The purpose of this tag is to declare what character set encoding the client's browser uses to display the page. xxx can be GB2312, GBK, UTF-8 (different from MySQL, which is UTF8), etc. Therefore, most pages can use this method to tell the browser what encoding to use when displaying this page, so as to avoid encoding errors and garbled characters. But sometimes we will find that this sentence still doesn't work. No matter which xxx is, the browser always uses the same encoding. I will talk about this later.

Please note that it belongs to HTML information and is just a statement. It works to indicate that the server has passed the HTML information to the browser.

　2. Use the header("content-type:text/html; charset=UTF-8"); function to set the page encoding

The function of this function header() is to send the information in the brackets to the http header.

If the content in the brackets is as mentioned in the article, then the function is basically the same as the label. If you compare it with the first one, you will find that the characters are similar. But the difference is that if there is this function, the browser will always use the xxx encoding you requested and will never be disobedient, so this function is very useful.

Why is this? Then we have to talk about the difference between HTTPS header and HTML information:

The https header is a string sent by the server before sending HTML information to the browser using the HTTP protocol.

Because the meta tag belongs to html information, the content sent by header() reaches the browser first. The popular point is that header() has a higher priority than meta. When adding a php page with both header("content-type:text/html; charset=xxx") and header("content-type:text/html; charset=xxx"), the browser will only recognize the former http header and not the meta. Of course, this function can only be used within PHP pages.

There cannot be any output in front, not even a single space, otherwise an error will be reported:

Warning: Cannot modify header information - headers already sent by (output started at C:wampwwwtest.php:2) in C:wampwwwtest.php on line 3

2. Database encoding

Before the PHP program queries the database, it first executes mysql_query("SET NAMES xxxx"); where xxxx is the encoding of your web page (charset=xxxx). If the web page has charset=utf8, then xxxx=utf8. If the web page has charset =gb2312, then xxxx=gb2312. Almost all WEB programs have a common code to connect to the database, which is placed in a file. In this file, just add mysql_query ("set names").

　SET NAMES Shows what character set is used in the SQL statement sent by the client. Therefore, the SET NAMES 'utf-8' statement tells the server that "future information from this client will use the character set utf-8." It also specifies the character set for the results that the server sends back to the client. (For example, if you use a SELECT statement, it indicates what character set is used for the column values.)

3. Unified PHP page encoding

MySQL database encoding, html page encoding, PHP or html file itself encoding must all be consistent.

1. MySQL database encoding: Specify the encoding (such as gbk_chinese_ci) when creating the database. Do not specify the encoding when creating data tables, creating fields, and inserting data. The encoding of the database will be automatically inherited.

When connecting to the database, there is also encoding. After connecting to the database, execute mysql_query('SET NAMES gbk');//replace gbk with your encoding, such as utf8.

2. The encoding of the html page refers to the setting of this line:

3. The encoding of the PHP or html file itself: Use editplus to open the php file or html file. When saving, select the encoding. If the database and page encoding is gbk, then the encoding here selects ansi; if the database and page encoding is utf-8, then utf-8 is also selected here.

4. Another thing to note is that the data passed in Javascript or Flash is encoded in utf-8. If the database and page encoding is gbk, it needs to be transcoded and then written to the database. iconv('utf-8', 'gbk', $content);

5. In the PHP program, you can add a line to specify the encoding of the PHP source program: header('Content-type: text/html; charset=gbk');

4. Differences in case of coded characters

(only in mysql, uppercase UTF-8, GBK, GB2312 is recommended elsewhere)

Only in MySQL, the alias "utf8" of "utf-8" can be used, but in other places, always use uppercase "UTF-8". Specifically: always use uppercase "UTF-8" outside the command "mysql_query(set names utf8)".