截取UTF-8编码下字符串的函数

/**

* 截取UTF-8编码下字符串的函数

*

* @param string str被截取的字符串∗@paramintlength 截取的长度

* @param bool append是否附加省略号∗∗@returnstring∗/functionsubstr(str, length=0,append = true)

{

str=trim(str);

strlength=strlen(str);

if ($length == 0 || $length >= $strlength)
{
return $str;
}
elseif ($length < 0)
{
$length = $strlength + $length;
if ($length < 0)
{
$length = $strlength;
}
}

if (function_exists('mb_substr'))
{
$newstr = mb_substr($str, 0, $length, 'utf-8');
}
elseif (function_exists('iconv_substr'))
{
$newstr = iconv_substr($str, 0, $length, utf-8);
}
else
{
//$newstr = trim_right(substr($str, 0, $length));
$newstr = substr($str, 0, $length);
}

if ($append && $str != $newstr)
{
$newstr .= '...';
}

return $newstr;

}