Chinese interception without garbled characters

Original Address:The method of realizing Chinese character string interception without garbled characters Author:Showan UTF-8 Chinese intercept function
In PHP, substr () function intercepts with Chinese strings, it may be garbled, this is because the Chinese and western languages a byte accounted for a different number of bytes, and substr length parameter is calculated according to bytes, in GB2312 encoding, a Chinese accounted for 2 bytes, English is 1 bytes, In UTF-8 encoding, a Chinese may occupy 2 or 3 bytes, and English or half-width punctuation is 1 bytes.
Workaround
UTF-8 encoded characters may consist of 1-3 bytes, and the exact number can be determined by the first byte.
The first byte is greater than 224, and it is composed of a UTF-8 character with 2 bytes after it
The first byte is greater than 192, which is less than 224, and it has a UTF-8 character with the 1 bytes after it, otherwise the first byte is itself an English character (including numbers and a small number of punctuation marks).
<?php
$a = "I am a programmer";
Class Dx
{
Private $str;
Public Function Msubstr ($string, $start, $length)
{
if (strlen ($string) > $length)
{
$n = 0;
$str = "";
$len = $start + $length;
for ($i = $start; $i < $len; $i + +)
{
if (Ord (substr ($string, $n, 1)) >224)
{
$str. =substr ($string, $n, 3);
$n +=3;
$i + +;
}
ElseIf (Ord (substr ($string, $n, 1)) >192)
{
$str. =substr ($string, $n, 2);
$i + +;
}
Else
{
$str. =substr ($string, $n, 1);