php utf-8和gb2312自动转化

	/**
	 * utf-8和gb2312自动转化
	 * @param unknown $string
	 * @param string $outEncoding
	 * @return unknown|string
	 */
	function safeEncoding($string,$outEncoding = 'UTF-8')
	{
		$encoding = "UTF-8";
		for($i = 0; $i < strlen ( $string ); $i ++) {
			if (ord ( $string {$i} ) < 128)
				continue;

			if ((ord ( $string {$i} ) & 224) == 224) {
				// 第一个字节判断通过
				$char = $string {++ $i};
				if ((ord ( $char ) & 128) == 128) {
					// 第二个字节判断通过
					$char = $string {++ $i};
					if ((ord ( $char ) & 128) == 128) {
						$encoding = "UTF-8";
						break;
					}
				}
			}
			if ((ord ( $string {$i} ) & 192) == 192) {
				// 第一个字节判断通过
				$char = $string {++ $i};
				if ((ord ( $char ) & 128) == 128) {
					// 第二个字节判断通过
					$encoding = "GB2312";
					break;
				}
			}
		}

		if (strtoupper ( $encoding ) == strtoupper ( $outEncoding ))
			return $string;
		else
			return @iconv ( $encoding, $outEncoding, $string );
	}