Important, if you're looking to trim/cut/truncate a string so that it will fit a certain byte size (for example to fit in a database field), look at:  mb_strcut()(PHP 4 >= 4.0.6, PHP 5, PHP 7, PHP 8)
mb_strwidth — Return width of string
   Returns the width of string string,
   where halfwidth characters count as 1, and fullwidth
   characters count as 2.
   See » http://www.unicode.org/reports/tr11/
   for details regarding East Asian character widths.
  
   The fullwidth characters are:
   U+1100-U+115F,
   U+11A3-U+11A7,
   U+11FA-U+11FF,
   U+2329-U+232A,
   U+2E80-U+2E99,
   U+2E9B-U+2EF3,
   U+2F00-U+2FD5,
   U+2FF0-U+2FFB,
   U+3000-U+303E,
   U+3041-U+3096,
   U+3099-U+30FF,
   U+3105-U+312D,
   U+3131-U+318E,
   U+3190-U+31BA,
   U+31C0-U+31E3,
   U+31F0-U+321E,
   U+3220-U+3247,
   U+3250-U+32FE,
   U+3300-U+4DBF,
   U+4E00-U+A48C,
   U+A490-U+A4C6,
   U+A960-U+A97C,
   U+AC00-U+D7A3,
   U+D7B0-U+D7C6,
   U+D7CB-U+D7FB,
   U+F900-U+FAFF,
   U+FE10-U+FE19,
   U+FE30-U+FE52,
   U+FE54-U+FE66,
   U+FE68-U+FE6B,
   U+FF01-U+FF60,
   U+FFE0-U+FFE6,
   U+1B000-U+1B001,
   U+1F200-U+1F202,
   U+1F210-U+1F23A,
   U+1F240-U+1F248,
   U+1F250-U+1F251,
   U+20000-U+2FFFD,
   U+30000-U+3FFFD.
   All other characters are halfwidth characters.
  
   The width of string string.
  
| Версія | Опис | 
|---|---|
| 8.0.0 | encodingтепер може бутиnull. | 
Приклад #1 mb_strwidth() example
<?php
var_dump(
    mb_strwidth('a'),       // LATIN SMALL LETTER A
    mb_strwidth("\u{ff41}") // FULLWIDTH LATIN SMALL LETTER A
);
?>Поданий вище приклад виведе:
int(1) int(2)
Important, if you're looking to trim/cut/truncate a string so that it will fit a certain byte size (for example to fit in a database field), look at:  mb_strcut()