众所周知，php 自带的 strlen 与 substr 函数没法处理中文字符，于是，我们会用 mb_ 系列函数替代。但是，没有 mbstring 库怎么办？这就需要我们自己写一个来替代了，废话不多说，先上代码
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if ( !function_exists('mb_strlen') ) {
function ($text, $encode) {
if ($encode=='UTF-8') {
return preg_match_all('%(?:
[x09x0Ax0Dx20-x7E] # ASCII
| [xC2-xDF][x80-xBF] # non-overlong 2-byte
| xE0[xA0-xBF][x80-xBF] # excluding overlongs
| [xE1-xECxEExEF][x80-xBF]{2} # straight 3-byte
| xED[x80-x9F][x80-xBF] # excluding surrogates
| xF0[x90-xBF][x80-xBF]{2} # planes 1-3
| [xF1-xF3][x80-xBF]{3} # planes 4-15
| xF4[x80-x8F][x80-xBF]{2} # plane 16
)%xs',$text,$out);
}else{
return strlen($text);
}
}
}
if (!function_exists('mb_substr')) {
function mb_substr($str, $start, $len = '', $encoding="UTF-8"){
$limit = strlen($str);
for ($s = 0; $start > 0;--$start) {
if ($s >= $limit)
break;
if ($str[$s] <= "x7F")
++$s;
else {
++$s;
while ($str[$s] >= "x80" && $str[$s] <= "xBF")
++$s;
}
}
if ($len == '')
return substr($str, $s);
else
for ($e = $s; $len > 0; --$len) {
if ($e >= $limit)
break;
if ($str[$e] <= "x7F")
++$e;
else {
++$e;
while ($str[$e] >= "x80" && $str[$e] <= "xBF" && $e < $limit)
++$e;
}
}
return substr($str, $s, $e - $s);
}
}
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