How to remove specified Chinese characters in php

With the continuous development of Internet technology, the PHP language has gradually become an indispensable part of Web development. In PHP, it is often necessary to process Chinese strings, but the encoding characteristics of Chinese characters make string processing complicated. This article will introduce how to use PHP to remove specified Chinese characters to solve this problem.

1. Understand Chinese character encoding

Chinese character encoding refers to the process of converting Chinese characters into binary codes that can be processed by computers. Different encoding methods will cause the same Chinese character to correspond to different binary codes under different encodings. Currently, the more commonly used Chinese encoding methods include GB2312, GBK, UTF-8, etc.

Let’s take a closer look at the UTF-8 encoding method. UTF-8 is a variable-length encoding method. One Chinese character can occupy 3 to 6 bytes. As shown in the figure below, UTF-8 encoded Chinese characters are represented by 1 to 3 bytes. The number of high-order bits of the first byte is 1 indicates the number of bytes occupied by the Chinese character.

#Due to the complexity of Chinese encoding, we need to be extra careful when processing Chinese strings in PHP.

2. Methods to remove specified Chinese characters in PHP

There are generally the following methods to remove specified Chinese characters in PHP:

1. Use regular expressions

Regular expression is a powerful text pattern matching tool that is very flexible in string processing. In PHP, you can use the preg_replace() function combined with regular expressions to quickly remove specified Chinese characters.

The following code demonstrates how to use regular expressions to remove the "programmer" character in a Chinese string:

$str = "我是一名程序员";
$pattern = "/程序员/u";
$replace = "";
$newstr = preg_replace($pattern, $replace, $str);
echo $newstr;

Among them, the " in the pattern string "/programmer/u" /u" means that Chinese characters are parsed in UTF-8 encoding. If you are using other encoding methods, you need to specify the corresponding mode according to different situations.

2. Looping through strings

Looping through strings is a relatively simple method and is also suitable for shorter Chinese strings. In the loop, you can remove the specified Chinese characters by judging whether the character's encoding value is within the specified range.

The following code demonstrates how to loop through a string and remove the "programmer" character in a Chinese string:

$str = "我是一名程序员";
$newstr = "";
for ($i = 0; $i  0x9FA5) {
        $newstr .= $char;
    }
}
echo $newstr;

Among them, mb_strlen() is used to obtain the length of the string, mb_substr () is used to obtain the character at the specified position in the string, and mb_ord() is used to obtain the Unicode encoding value of the character. The "mb" in the function name indicates that these functions are for multi-byte strings.

It is worth noting that the above code can only remove "programmer" in the Chinese string. If you want to remove other Chinese characters, you need to judge based on the range of its encoding value.

3. Summary

This article introduces two methods to remove specified Chinese characters in PHP: using regular expressions and looping through strings. It should be noted that for relatively long Chinese strings and Chinese strings in other encoding methods such as BLK or GB2312, these methods may cause performance problems or coding errors. Therefore, it is necessary to choose the most suitable method based on the actual situation. .

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