About UPC-A barcode symbol structure

　　The UPC-A barcode is used to identify the UCC-12 barcode. It is A barcode system formulated by the United States Unified Code Commission (UCC). It is mainly used in the United States and Canada, and is the most widely used UPC code. Next, I will give you a detailed introduction of UPC code.

　　The six bar code characters on the left of UPC-A bar code are composed of bar code characters of A subset, and the data character and check character on the right are composed of bar code characters of C subset, which is UPC-A bar code, that is, UPC-A bar code is A special form of EAN-13 bar code, UPC-A bar code is compatible with THE N1 = "0" in EAN-13 code. It also indicates that upC-A bar code has bidirectional readability. Because the bar code characters on the left and right sides are composed of bar code characters of different subsets, no matter which side you start reading from, you can quickly identify the corresponding left and right sides.

　　The first digit character on the left of the UPC-A barcode is the system character, and the last character is the check character. They are placed outside the start character and the stop character respectively. In addition, the bar length of the bar code character representing the system character and the check character and the bar length of the stop character, etc.

　　Check code algorithm: Start from the country code and take the numbers from left to right. Set the codes of each UPC-A as follows :N1 N2 N3 N4 N5 N6 N7 N8 N9 N10 N11 C Then calculate the check codes as follows: C1 =( N1+ N3+N5+N7+N9+N11)*3 C2 =N2+N4+N6+N8+N10

　　CC = (C1+C2) take the units digit C (check code) = 10 - CC (0 if 10)

　　In specific cases, the 12-bit UPC-A bar code can be represented as A shortened form of bar code symbol, namely UPC-E bar code. Upc-e bar code is special in that it only directly represents six data characters. The bar code symbol itself has no middle separator and the terminator is different from UPC-A.

　　The height of the UPC-E bar code symbol is the same as that of the UPC-A bar code symbol, but the length is greatly shortened.

　　The above is the introduction of UPC - A barcode symbol. Upc-a code is used for general products, and different commodity types and countries may have different types of barcode.