PHP uses the mb_string function library to process Chinese characters related to windows, _PHP tutorial

PHP uses the mb_string function library to process Chinese characters related to windows.

Yesterday I wanted to batch process a bunch of files I downloaded before, and use regular expressions to match the key contents in the files, and focus on deal with. A problem encountered when operating files is the encoding problem in the Windows operating system.

We all know that in Windows (Chinese version of course), the encoding of file names and file contents are gbk, and during our development process, the encoding in the IDE is UTF-8 , (I won’t discuss why and so on here,

Only consider how to convert the encoding to the same), so the Chinese in the UTF-8 encoded regular pattern string I wrote cannot be correctly matched in the gbk encoded file.

At first, I had no idea. I tried changing the encoding of the PHP script file to GBK, which also worked, but I thought this method was too low, so I looked for any functions in PHP that could satisfy me. needs.

At this time, I thought of the function iconv() that I used to process file names in windows. The function prototype is as follows:

<p>string iconv ( string $in_charset , string $out_charset , string $str )</p>
<p>Performs a character set conversion on the string str from in_charset to out_charset. </p>

We often use:

<span>$out_charset</span>='utf-8'<span>;

</span><span>$fileName</span>=<span>iconv</span>(<span>$fileName</span>,<span>$out_charset</span>,'gbk');

to process the file name, change the file name from gbk to UTF-8 without changing the content.

Manual translation appended:

• If you add //TRANSLIT after the output string $out_charset, that is, $out_charset='utf-8//TRANSLIT', when encountering a character that cannot be converted to UTF-8, the program will automatically replace it with a similar character UTF-8 characters;
• If you add //IGNORE after the output string $out_charset, that is, $out_charset='utf-8//IGNORE', when encountering a character that cannot be converted to UTF-8, the program will automatically skip this character.
• If you add nothing, the replacement will be interrupted when a character that cannot be replaced with UTF-8 is encountered.

However, when I use this function to process, the result is like this:

It means that the maximum number of characters that the iconv() function can handle is only 64, which is the size of a general file name, and the content of my file is obviously more than 64 characters.

There was no other way, so I had to look for other functions again.

Until I discovered the mb_string function library, this function library is generally integrated in the PHP environment. We can find it in phpinfo().

mb_convert_encoding() function in the mb_string function, which can change the encoding of a string. The function prototype is as follows:

<p>string mb_convert_encoding ( string $str , string $to_encoding [, mixed $from_encoding ] )</p>
<p>Converts the character encoding of string str to to_encoding from optionally from_encoding. </p>

The basic prototype is similar to the iconv() function, except that it does not have suffix modifications on the output function, and it does not have a clear limit on the length of the string.

And we see that $from_encoding is optional, it can automatically identify the source encoding.

Because it cannot find an exact character that cannot be transcoded, and I don’t know what it will do when it encounters characters that cannot be transcoded.

The entire file was processed through the mb_convert_encoding() function, and the problem was successfully solved.

Finally, let’s introduce the mb_string function library. Its full name is Multibyte String. Many of its methods are extended from PHP’s own string function library. The function name is added in front of the original function. "mb_" has been removed. In addition to having the functions of the original function, these functions also add an optional parameter of $encoding at the end of the optional parameters. This parameter can specify the encoding method of the function. Process strings.

For example, the strpos() function finds the position of a string in another string.

strpos("Welcome to visit","Ask",0) returns a result of 12, because the script is UTF-8 encoded, and after converting the string to UTF-8 encoding, each Chinese character will occupy 3 bytes.

In the mb_strpos() function, mb_strpos("Welcome to visit", "Ask", 0, 'utf-8') will return 4, which will treat the string as having been converted to UTF-8 implement.

And mb_strpos("Welcome to visit","Ask",0,'gbk') will return 6

Of course, it has more unique features~

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