function sub_str($str, $length = 0, $append = true)
{
$str = trim($str);
$strlength = strlen($str);if ($length == 0 || $length >= $strlength)
{
return $str; //截取长度等于0或大于等于本字符串的长度,返回字符串本身
}
elseif ($length < 0) //如果截取长度为负数
{
$length = $strlength + $length;//那么截取长度就等于字符串长度减去截取长度
if ($length < 0)
{
$length = $strlength;//如果截取长度的绝对值大于字符串本身长度,则截取长度取字符串本身的长度
}
}if (function_exists(‘mb_substr’))
{
$newstr = mb_substr($str, 0, $length, EC_CHARSET);
}
elseif (function_exists(‘iconv_substr’))
{
$newstr = iconv_substr($str, 0, $length, EC_CHARSET);
}
else
{
//$newstr = trim_right(substr($str, 0, $length));
$newstr = substr($str, 0, $length);
}if ($append && $str != $newstr)
{
$newstr .= ‘…’;
}return $newstr;
}