Detailed explanation of PHP page encoding declaration method (header or meta)

php header to define a php page as utf encoding or GBK encoding

php page as utf encoding
header("Content-type: text/html; charset=utf-8");

The php page is encoded by gbk
header("Content-type: text/html; charset=gb2312");

The php page is encoded by big5
header("Content- type: text/html; charset=big5");

Usually the above code is placed on the home page of the PHP page

The difference between using header or meta to implement PHP page encoding
1. Page Encoding

1. Use the tag to set the page encoding

The function of this tag is 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 situation later.

Please note that 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. header("content-type:text/html; charset=xxx");

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, the function is basically the same as the tag. 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 so? 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 transmitting 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 (I don’t know if this can be said). Add a php page that has both header("content-type:text/html; charset=xxx") and , 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 is also a question left, why does the former definitely work, but the latter sometimes doesn’t? This is why we want to talk about Apache next.

3. AddDefaultCharset

In the conf folder in the root directory of Apache, there is the entire Apache configuration document httpd.conf.

Open httpd.conf with a text editor. Line 708 (different versions may be different) contains AddDefaultCharset xxx, where xxx is the encoding name. The meaning of this line of code: Set the character set in the https header of the web page file in the entire server to your default xxx character set. Having this line is equivalent to adding a header ("content-type: text/html; charset=xxx") to each file. Now you can understand why the browser always uses gb2312 even though the meta setting is utf-8.

If there is a header("content-type:text/html; charset=xxx") in the web page, the default character set will be changed to the character set you set, so this function will always be useful. If you add a "#" in front of AddDefaultCharset xxx, comment out this sentence, and the page does not contain header ("content-type..."), then it is the meta tag's turn to take effect.

Summary:

Let’s sort

header("content-type:text/html; charset=xxx")
AddDefaultCharset xxx

If you are a web programmer, add a header("content-type:text/ html; charset=xxx"), ensuring that it can be displayed correctly on any server and has strong portability.

As for the sentence AddDefaultCharset xxx, whether it should be commented or not is a matter of opinion. Anyway, I commented it out, but I also need to write header() when writing a page, so that it can be displayed normally on the server.

2. Database encoding

Before querying the database, the PHP program first executes mysql_query("SET NAMES xxxx"); where xxxx is the encoding of your web page (charset=xxxx). If the web page charset=utf8, then xxxx=utf8. If charset=gb2312 in the web page, 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, add mysql_query(" set names") will do.

SET NAMES Shows what character set is used in SQL statements 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 value.)

PHP page encoding is unified

MySQL database encoding, html page encoding, PHP or html file itself The coding must be consistent across all.
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, and when saving, select the encoding. If the database and page encoding is gbk, select ansi for the encoding here; if the database and page encoding are The page encoding is utf-8, so select utf-8 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');

For more detailed explanations of PHP page encoding declaration methods (header or meta), please pay attention to the PHP Chinese website!