{"resolved":true,"match_type":"uuid","source_type":"original_book","book_id":"38270854-596f-4a26-8183-db8c968c6020","title":"编码 隐匿在计算机软硬件背后的语言","author":null,"edition":null,"publisher":null,"year":null,"isbn":"9787121181184","requested_by":"printed_page","book":{"source_type":"original_book","book_id":"38270854-596f-4a26-8183-db8c968c6020","id":"38270854-596f-4a26-8183-db8c968c6020","uuid":"38270854-596f-4a26-8183-db8c968c6020","title":"编码 隐匿在计算机软硬件背后的语言","normalized_title":"编码隐匿在计算机软硬件背后的语言","author":null,"edition":null,"publisher":null,"year":null,"isbn":"9787121181184","isbns":["9787121181184","0123456789","6044921875","3039331000","0000000000","0000000000000"],"parsed":true,"ai_readable":true,"document_type":"book","page_count":438,"navigation_url":"https://workshop.closeclaw.top/ai/book/38270854-596f-4a26-8183-db8c968c6020","title_url":"https://workshop.closeclaw.top/ai/title/%E7%BC%96%E7%A0%81%20%E9%9A%90%E5%8C%BF%E5%9C%A8%E8%AE%A1%E7%AE%97%E6%9C%BA%E8%BD%AF%E7%A1%AC%E4%BB%B6%E8%83%8C%E5%90%8E%E7%9A%84%E8%AF%AD%E8%A8%80","fixed_page_url_template":"https://workshop.closeclaw.top/ai/book/38270854-596f-4a26-8183-db8c968c6020/page/{printed_page}","path_api_url_template":"https://workshop.closeclaw.top/api/ai/book/38270854-596f-4a26-8183-db8c968c6020/page/{printed_page}","read_url":"https://workshop.closeclaw.top/api/ai/read/38270854-596f-4a26-8183-db8c968c6020","page_url":"https://workshop.closeclaw.top/api/ai/books/38270854-596f-4a26-8183-db8c968c6020/page","search_url":"https://workshop.closeclaw.top/api/ai/books/38270854-596f-4a26-8183-db8c968c6020/search"},"page":{"printed_page":85,"pdf_page":101,"physical_index":101,"physical_index_base":0,"printed_page_status":"recognized","page_sha256":"c5f2a8ec2d6148e3420f249088ddb3d871d70110f8d0fa30348712859ad8641c"},"chapter":"编码隐匿在计算机软硬件背后的语言","content":"破解右边的6组7位编码要用到下表。\n\n右边的编码\n\n$$\n1 1 1 0 0 1 0 = 0 \\quad\n$$\n\n$$\n1 0 0 1 1 1 0 = 5 \n$$\n\n$$\n1 1 0 0 1 1 0 = 1\n$$\n\n$$\n1 0 1 0 0 0 0 = 6 \n$$\n\n$$\n1 1 0 1 1 0 0 = 2 \n$$\n\n$$\n1 0 0 0 1 0 0 = 7 \\ \\AA\n$$\n\n$$\n1 0 0 0 0 1 0 = 3\n$$\n\n$$\n1 0 0 1 0 0 0 = 8 \n$$\n\n$$\n1 0 1 1 1 0 0 = 4\n$$\n\n$$\n1 1 1 0 1 0 0 = 9\n$$\n\n这些编码都是之前编码的补码：之前出现0的地方，现在都换成了1，反之亦然。这些编码都是以1开头，以0结尾的。除此之外，每组编码都含有偶数个1，属于偶校验。\n\n现在，我们就可以解读UPC了。运用以上两个表格，我们可以确定，Campbell公司的103/4盎司罐装鸡汁面汤包上的12个数字为：\n\n0 51000 01251 7\n\n太令人失望了。就如你所看到的，这与UPC下面印刷的数字完全相同（这样做是很有意义的，在扫描仪由于某种原因无法解读出条形码时，收银员就可以手动输入这些数字，毫无疑问你也看到过这一幕)。我们没有必要了解解码的全部过程，况且，我们也无法从中解码出任何秘密信息。不过，关于UPC的解码工作已经没有什么可做了，那30根竖条已经变成了12个数字。\n\n第一个数字（在这里是0）被称为数字系统符。0意味着这是一个常规的UPC。如果UPC出现在杂货店中那些需要称重的商品上，例如肉、农产品，这个编码就会是2。票券的UPC的第一个数字通常是5。\n\n接下来的5个数字表示制造商编码。这种情况下，51000就是Campbell公司的编码。所有Campbell公司的产品都有这个编码。后面的5位代码（01251）是这个公司的某种商品的编码，上例中这个数字就是指103/4盎司罐装鸡汁面。只有和制造商编码同时出现的时候这个编码才有意义。另一个公司的鸡汁面会有另外一个编码，01251在另外一个公\n\n9 二进制数\n\n85","previous_page":84,"next_page":86}