PHP - Manual: mb_strcut

2024-11-23

mb_strcut

(PHP 4 >= 4.0.6, PHP 5, PHP 7, PHP 8)

mb_strcut — 获取字符的一部分

说明

mb_strcut(
    string $str,
    int $start,
    int $length = NULL,
    string $encoding = mb_internal_encoding()
): string

mb_strcut() 和 mb_substr() 类似，都是从字符串中提取子字符串，但是按字节数来执行，而不是字符个数。如果截断位置位于多字节字符两个字节的中间，将于该字符的第一个字节开始执行。这也是和 substr() 函数的不同之处，后者简单地将字符串在字节之间截断，这将导致一个畸形的字节序列。

参数

str

要截断的 string。

start

如果 start 不是负数，返回的字符串会从 str 的第 start 字节位置开始，从 0 开始计数。举个例子，字符串 'abcdef'，字节位置 0 的字符是 'a'，字节位置 2 的字符是 'c'，以此类推。

如果 start 是负数，返回的字符串是从 str 末尾处第 start 个字节开始的。

length

字节长度。If omitted or NULL is passed, extract all bytes to the end of the string.

encoding

encoding 参数为字符编码。如果省略或是 null，则使用内部字符编码。

返回值

mb_strcut() 根据 start 和 length 参数返回 str 的一部分。

更新日志

版本	说明
5.4.8	Passing `NULL` as `length` extracts all bytes to the end of the string. Prior to this version `NULL` was treated the same as `0`.

参见

mb_substr() - 获取部分字符串
mb_internal_encoding() - 设置/获取内部字符编码

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User Contributed Notes 5 notes

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t dot starling at physics dot unimelb dot edu dot au ¶

17 years ago


What the manual and the first commenter are trying to say is that mb_strcut uses byte offsets, as opposed to mb_substr which uses character offsets. 

Both mb_strcut and mb_substr appear to treat negative and out-of-range offsets and lengths in the basically the same way as substr. An exception is that if start is too large, an empty string will be returned rather than FALSE. Testing indicates that mb_strcut first works out start and end byte offsets, then moves each offset left to the nearest character boundary.

down

olivthill at gmail dot com ¶

4 years ago


Here is an example with UTF8 characters, to see how the start and length arguments are working:

  $str_utf8 = utf8_encode("Déjà_vu");
  $str_utf8_0 = mb_strcut($str_utf8, 0, 4, "UTF-8"); // Déj
  $str_utf8_1 = mb_strcut($str_utf8, 1, 4, "UTF-8"); // éj
  $str_utf8_2 = mb_strcut($str_utf8, 2, 4, "UTF-8"); // éj
  $str_utf8_3 = mb_strcut($str_utf8, 3, 4, "UTF-8"); // jà_
  $str_utf8_4 = mb_strcut($str_utf8, 4, 4, "UTF-8"); // à_v

The string includes two special charaters, "é" and "à" internally coded with two bytes.
Note that a multibyte character is removed rather than kept in half at the end of the output.
Note also that the result is the same for a cut 1,4 and a cut 2,4 with this string.

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oyag02 at yahoo dot co dot jp ¶

18 years ago


diffrence between mb_substr and mb_substr

example:
mb_strcut('I_ROHA', 1, 2) returns 'I_'. Treated as byte stream.
mb_substr('I_ROHA', 1, 2) returns 'ROHA' Treated as character stream.

# 'I_' 'RO' 'HA' means multi-byte character

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-1

David Juhasz ¶

7 months ago


This was driving me crazy, because mb_strcut() kept returning an empty string.  The $length parameter seems to have a max value of 2^32-1 (2147483647).

Works:
<?php
  # output: Полуустав
  echo mb_strcut('Полуустав', 0, pow(2,31)-1);
?>

Doesn't work:
<?php
  # nothing is output
  echo mb_strcut('Полуустав', 0, pow(2,31));
?>

My PHP_INT_MAX value is much larger than 2^32-1, so I'm not sure why larger values for $length don't work. :(

<?php
  # output: 9223372036854775807
  echo PHP_INT_MAX;
?>

down

-23

php_engineer_bk at yahoo dot com ¶

11 years ago


function cut_sense($matne_harf, $l_harf ,$return=1 ) {
if ( strlen($matne_harf) > $l_harf){
$end='...';
}else{
$end='';
}
    if ( function_exists('mb_strcut') ){
        $matne_harf = mb_strcut ( $matne_harf, 0 , $l_harf , "UTF-8" );
    }else{
        $matne_harf =substr($matne_harf, 0, $l_harf);
    }
$text=''.$matne_harf.''.$end.'';
  if ( $return == 1){
  return $text;
  }else{
  print $text;
  }
}

Iranian php programmer (farhad zand +989383015266)

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官方地址：https://www.php.net/manual/en/function.mb-strcut.php

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PHP官方手册 - 互联网笔记

mb_strcut

说明

参数

返回值

更新日志

参见

User Contributed Notes 5 notes