What should I do if Chinese garbled characters appear when using substr() to intercept strings in PHP?_PHP Tutorial

What should I do if the problem of Chinese garbled characters occurs when using substr() to intercept strings in PHP?

In PHP program development, string interception operations are often performed, such as outputting information. When making a list, the title should not be too long. When printing the article abstract, a series of string interception operations must also be performed. When encountering these requirements, we often think of using the substr() method to achieve it. substr() is more suitable for intercepting all-English strings.

But as long as Chinese characters appear in the string, it may cause PHP substr Chinese garbled characters, because Chinese UTF-8 encoding, each Chinese character occupies 3 bytes, while GB2312 occupies 2 bytes, and English occupies 1 byte, interception bit The number is inaccurate. substr() forcibly "saws" a Chinese character in half, causing the broken character to pull the following... together to make a word, so PHP substr Chinese garbled characters appear.

substr --- Get part of the string

Syntax: string substr (string string, int start [, int length])

Description:

substr() returns a part of string, specified by the parameters start and length.

If start is a positive number, the returned string will start from the start character of string.

Example :

<&#63;php
$rest = substr ("abcdef", 1); // returns "bcdef"
$rest = substr ("abcdef", 1, 3); // returns "bcd"
&#63;>

If start is a negative number, the returned string will start from the start character at the end of string.

Example :

<&#63;php
$rest = substr ("abcdef", -1); // returns "f"
$rest = substr ("abcdef", -2); // returns "ef"
$rest = substr ("abcdef", -3, 1); // returns "d"
&#63;>

If the parameter length is given and is a positive number, the returned string will be length characters from start.
If the length parameter is given and is a negative number, the returned string will end at the length-th character from the end of string.

Example :

<&#63;php
$rest = substr ("abcdef", 1, -1); // returns "bcde"
&#63;>

No problem for English, we test a Chinese one

<&#63;php
$rest = substr ("中国人", 1, -1); // returns "fdsafsda" 就是乱码了
&#63;>

The result of this kind of character interception is definitely not the result we want. This situation of Chinese garbled PHP substr may cause the program to fail to run normally. There are two main solutions:

1. Use mb_substr() of the mbstring extension library to intercept, and there will be no garbled characters.

You can use the function mb_substr()/mb_strcut(). The usage of mb_substr()/mb_strcut() is similar to substr(), except that one more parameter needs to be added at the end of mb_substr()/mb_strcut to set the string. Encoding, but most servers do not open php_mbstring.dll. You need to open php_mbstring.dll in php.ini.

<&#63;php
  echo mb_substr("php中文字符encode",0,4,"utf-8");
&#63;>

If the last encoding parameter is not specified, three bytes will be used as one Chinese character. This is the characteristic of utf-8 encoding. If the utf-8 character set description is added, it will be intercepted in units of one word. of.

When using it, pay attention to the encoding of the php file and the encoding when displaying the web page. To use this mb_substr method, you need to know the encoding of the string in advance. If you don't know the encoding, you need to judge. The mbstring library also provides mb_check_encoding to check the string encoding, but it is not perfect yet.

PHP comes with several string interception functions, among which substr and mb_substr are commonly used. When the former processes Chinese, GBK is 2 length units and UTF is 3 length units. After the latter specifies encoding, one Chinese character is 1 length unit.

substr sometimes cuts off 1/3 Chinese or half Chinese and displays garbled characters. Relatively speaking, mb_substr is more suitable for us to use. But sometimes mb_substr doesn't seem so useful. For example, if I want to display the brief information of a small picture, 5 Chinese characters are just right. If there are more than 5 characters, just intercept the first 4 and add "...". This is no problem when processing Chinese, but when processing English or numbers, this interception will be too short. .

2. Write the interception function yourself, but the efficiency is not as high as using the mbstring extension library. The following is a function in ecshop that intercepts strings encoded in UTF-8.

function sub_str($str, $length = , $append = true)
{
  $str = trim($str);
  $strlength = strlen($str);
  if ($length == || $length >= $strlength)
  {
    return $str; //截取长度等于或大于等于本字符串的长度，返回字符串本身
  }
  elseif ($length < ) //如果截取长度为负数
  {
    $length = $strlength + $length;//那么截取长度就等于字符串长度减去截取长度
    if ($length < )
    {
      $length = $strlength;//如果截取长度的绝对值大于字符串本身长度，则截取长度取字符串本身的长度
    }
  }
  if (function_exists('mb_substr'))
  {
    $newstr = mb_substr($str, , $length, EC_CHARSET);
  }
  elseif (function_exists('iconv_substr'))
  {
    $newstr = iconv_substr($str, , $length, EC_CHARSET);
  }
  else
  {
    //$newstr = trim_right(substr($str, , $length));
    $newstr = substr($str, , $length);
  }
  if ($append && $str != $newstr)
  {
    $newstr .= '...';
  }
  return $newstr;
}

Okay, that’s all the description in this article. I believe it will be useful to everyone. The above code is also very simple. If you have anything you don’t understand, please leave me a message and I will reply to you as soon as possible.

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