如何将 UPC-A 转换为 UPC-E？

Question

我们想将 12 位 UPC-A 转换为 8 位 UPC-E。你能告诉我最好的方法是不用我自己的代码来转换吗？

我有很多公式可以将 8 位 UCC-E 转换为 12 位 UPC-A 但不能反转。

Answer 1

            NSString *strScannedCode = @"028200002921";
        NSString *strBarCodeType = @"UPC E";

        NSString *strAlteredScannedCode = strScannedCode;

        if ([strBarCodeType isEqualToString:@"UPC E"])
        {
            if (strScannedCode.length == 12)
            {
                NSString *strManufacturerCode = [strScannedCode substringWithRange:(NSMakeRange(1, 5))];
                NSString *strProductCode = [strScannedCode substringWithRange:NSMakeRange(6, 5)];

                NSLog(@"strManufacturerCode = %@",strManufacturerCode);
                NSLog(@"strProductCode = %@",strProductCode);

                if ([[strManufacturerCode substringWithRange:NSMakeRange(2, 3)] isEqualToString:@"000"] ||
                    [[strManufacturerCode substringWithRange:NSMakeRange(2, 3)] isEqualToString:@"100"] ||
                    [[strManufacturerCode substringWithRange:NSMakeRange(2, 3)] isEqualToString:@"200"])
                {
                    strAlteredScannedCode = STRING(@"%@%@%@",[strManufacturerCode substringWithRange:NSMakeRange(0, 2)],
                                                   [strProductCode substringWithRange:NSMakeRange(2, 3)],
                                                   [strManufacturerCode substringWithRange:NSMakeRange(2, 1)]);
                }
                else if ([[strManufacturerCode substringWithRange:NSMakeRange(3, 2)] isEqualToString:@"00"])
                {
                    strAlteredScannedCode = STRING(@"%@%@3",[strManufacturerCode substringWithRange:NSMakeRange(0, 3)],
                                                   [strProductCode substringWithRange:NSMakeRange(3, 2)]);

                }
                else if ([strManufacturerCode characterAtIndex:4] == '0')
                {
                    strAlteredScannedCode = STRING(@"%@%@4",[strManufacturerCode substringWithRange:NSMakeRange(0, 4)],
                                                   [strProductCode substringWithRange:NSMakeRange(4, 1)]);
                }
                else if ([strManufacturerCode characterAtIndex:4] != '0')
                {
                    strAlteredScannedCode = STRING(@"%@%@",strManufacturerCode,
                                                   [strProductCode substringWithRange:NSMakeRange(4, 1)]);
                }

                strAlteredScannedCode = STRING(@"%@%@%@",[strScannedCode substringWithRange:NSMakeRange(0, 1)],strAlteredScannedCode,[strScannedCode substringWithRange:NSMakeRange(11, 1)]);

                NSLog(@"strUPC_E_Code = %@",strAlteredScannedCode);
            }
        }

By implementing above code you will get 12 digit to 8 digit, For Example you will get result as "02829221", This is UPC E of "028200002921".

Answer 2

从以下模式映射中可以最清楚地看出在 UPC-A 和 UPC-E 表示之间转换 GTIN-12 标识符的算法：

SabN0000cdeX ⟺ SabcdeNX  :  0≤N≤2
Sabc00000deX ⟺ Sabcde3X
Sabcd00000eX ⟺ Sabcde4X
Sabcde0000NX ⟺ SabcdeNX  :  5≤N≤9

上面的S是数制，0或者1，X是校验位。如果 UPC-A 与模式不匹配，则无法将其转换为 UPC-E。

It can be seen that there may be up to four valid UPC-E representations of each UPC-A:

001200000067 ⟺ 00100627 ⟺ 00120637 ⟺ 00120647 ⟺ 00120067.

执行从 UPC-A 到 UPC-E 的一种转换方法的伪代码如下所示：

Input:  A valid twelve-digit UPC-A: Assigned to A[]. 
Output: PASS: Eight-digit UPC-E representing the UPC-A.
        FAIL: Reason.

if A[0] != {0-1} then FAIL: Invalid number system.

if A[3] == {0-2} && A[4..7] == "0000"  then PASS: A[0..2] . A[8..10] . A[3]  . A[11]
if A[4..8] == "00000"                  then PASS: A[0..3] . A[9..10] . "3"   . A[11]
if A[5..9] == "00000"                  then PASS: A[0..4] . A[10]    . "4"   . A[11]
if A[6..9] == "0000" && A[10] == {5-9} then PASS: A[0..5] .            A[10] . A[11]

otherwise, FAIL: UPC-A not compatible with UPC-E.

如何将 UPC-A 转换为 UPC-E？

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