編碼轉化

/**
 * utf8轉gbk
 *
 * @param
 *        	$utfstr
 */
function utf8_to_gbk($utfstr) {
	global $UC2GBTABLE;
	$okstr = '';
	if (empty ( $UC2GBTABLE )) {
		$filename = CODETABLEDIR . 'gb-unicode.table';
		$fp = fopen ( $filename, 'rb' );
		while ( $l = fgets ( $fp, 15 ) ) {
			$UC2GBTABLE [hexdec ( substr ( $l, 7, 6 ) )] = hexdec ( substr ( $l, 0, 6 ) );
		}
		fclose ( $fp );
	}
	$okstr = '';
	$ulen = strlen ( $utfstr );
	for($i = 0; $i < $ulen; $i ++) {
		$c = $utfstr [$i];
		$cb = decbin ( ord ( $utfstr [$i] ) );
		if (strlen ( $cb ) == 8) {
			$csize = strpos ( decbin ( ord ( $cb ) ), '0' );
			for($j = 0; $j < $csize; $j ++) {
				$i ++;
				$c .= $utfstr [$i];
			}
			$c = utf8_to_unicode ( $c );
			if (isset ( $UC2GBTABLE [$c] )) {
				$c = dechex ( $UC2GBTABLE [$c] + 0x8080 );
				$okstr .= chr ( hexdec ( $c [0] . $c [1] ) ) . chr ( hexdec ( $c [2] . $c [3] ) );
			} else {
				$okstr .= '&#' . $c . ';';
			}
		} else {
			$okstr .= $c;
		}
	}
	$okstr = trim ( $okstr );
	return $okstr;
}

/**
 * gbk轉utf8
 *
 * @param
 *        	$gbstr
 */
function gbk_to_utf8($gbstr) {
	global $CODETABLE;
	if (empty ( $CODETABLE )) {
		$filename = CODETABLEDIR . 'gb-unicode.table';
		$fp = fopen ( $filename, 'rb' );
		while ( $l = fgets ( $fp, 15 ) ) {
			$CODETABLE [hexdec ( substr ( $l, 0, 6 ) )] = substr ( $l, 7, 6 );
		}
		fclose ( $fp );
	}
	$ret = '';
	$utf8 = '';
	while ( $gbstr ) {
		if (ord ( substr ( $gbstr, 0, 1 ) ) > 0x80) {
			$thisW = substr ( $gbstr, 0, 2 );
			$gbstr = substr ( $gbstr, 2, strlen ( $gbstr ) );
			$utf8 = '';
			@$utf8 = unicode_to_utf8 ( hexdec ( $CODETABLE [hexdec ( bin2hex ( $thisW ) ) - 0x8080] ) );
			if ($utf8 != '') {
				for($i = 0; $i < strlen ( $utf8 ); $i += 3)
					$ret .= chr ( substr ( $utf8, $i, 3 ) );
			}
		} else {
			$ret .= substr ( $gbstr, 0, 1 );
			$gbstr = substr ( $gbstr, 1, strlen ( $gbstr ) );
		}
	}
	return $ret;
}

/**
 * unicode轉utf8
 *
 * @param
 *        	$c
 */
function unicode_to_utf8($c) {
	$str = '';
	if ($c < 0x80) {
		$str .= $c;
	} elseif ($c < 0x800) {
		$str .= (0xC0 | $c >> 6);
		$str .= (0x80 | $c & 0x3F);
	} elseif ($c < 0x10000) {
		$str .= (0xE0 | $c >> 12);
		$str .= (0x80 | $c >> 6 & 0x3F);
		$str .= (0x80 | $c & 0x3F);
	} elseif ($c < 0x200000) {
		$str .= (0xF0 | $c >> 18);
		$str .= (0x80 | $c >> 12 & 0x3F);
		$str .= (0x80 | $c >> 6 & 0x3F);
		$str .= (0x80 | $c & 0x3F);
	}
	return $str;
}
/**
 * utf8轉unicode
 *
 * @param
 *        	$c
 */
function utf8_to_unicode($c) {
	switch (strlen ( $c )) {
		case 1 :
			return ord ( $c );
		case 2 :
			$n = (ord ( $c [0] ) & 0x3f) << 6;
			$n += ord ( $c [1] ) & 0x3f;
			return $n;
		case 3 :
			$n = (ord ( $c [0] ) & 0x1f) << 12;
			$n += (ord ( $c [1] ) & 0x3f) << 6;
			$n += ord ( $c [2] ) & 0x3f;
			return $n;
		case 4 :
			$n = (ord ( $c [0] ) & 0x0f) << 18;
			$n += (ord ( $c [1] ) & 0x3f) << 12;
			$n += (ord ( $c [2] ) & 0x3f) << 6;
			$n += ord ( $c [3] ) & 0x3f;
			return $n;
	}
}