php截取字符串之截取utf8或gbk编码的中英文字符串示例

function strlen_weibo($string, $charset='utf-8')
{
$n = $count = 0;
$length = strlen($string);
if (strtolower($charset) == 'utf-8')
{
while ($n < $length)
{
$currentByte = ord($string[$n]);
if ($currentByte == 9 ||
$currentByte == 10 ||
(32 <= $currentByte && $currentByte <= 126))
{
$n++;
$count++;
} elseif (194 <= $currentByte && $currentByte <= 223)
{
$n += 2;
$count += 2;
} elseif (224 <= $currentByte && $currentByte <= 239)
{
$n += 3;
$count += 2;
} elseif (240 <= $currentByte && $currentByte <= 247)
{
$n += 4;
$count += 2;
} elseif (248 <= $currentByte && $currentByte <= 251)
{
$n += 5;
$count += 2;
} elseif ($currentByte == 252 || $currentByte == 253)
{
$n += 6;
$count += 2;
} else
{
$n++;
$count++;
}
if ($count >= $length)
{
break;
}
}
return $count;
} else
{
for ($i = 0; $i < $length; $i++)
{
if (ord($string[$i]) > 127)
{
$i++;
$count++;
}
$count++;
}
return $count;
}
}