How to determine if a number is a UPC code or just a simple number? Is there any specific format for identifying a UPC code?

Question

Is there any format we can use to identify the UPC code instead of checking only the number of digits?

Answer 1

I have an Objective-C code that checks a user input string to see if it is a valid UPC or EAN barcode. It supports UPC, ISBN and EAN (8, 13 and 14).

If you have a number, first convert it to a string to use this method. This method assumes that the barcode string only has digits 0-9 or X (some ISBN barcodes may have X).

- (BOOL)validBarcode:(NSString *)code { int len = [code length]; switch (len) { case 8: // EAN-8 { int check = [code intForDigitAt:7]; int val = (10 - (([code intForDigitAt:1] + [code intForDigitAt:3] + [code intForDigitAt:5] + ([code intForDigitAt:0] + [code intForDigitAt:2] + [code intForDigitAt:4] + [code intForDigitAt:6]) * 3) % 10)) % 10; return check == val; } case 10: // ISBN { int check = [code intForDigitAt:9]; int sum = 0; for (int i = 0; i < 9; i++) { sum += [code intForDigitAt:i] * (i + 1); } int val = sum % 11; if (val == 10) { return [code characterAtIndex:9] == 'X' || [code characterAtIndex:9] == 'x'; } else { return check == val; } } case 12: // UPC { int check = [code intForDigitAt:11]; int val = (10 - (([code intForDigitAt:1] + [code intForDigitAt:3] + [code intForDigitAt:5] + [code intForDigitAt:7] + [code intForDigitAt:9] + ([code intForDigitAt:0] + [code intForDigitAt:2] + [code intForDigitAt:4] + [code intForDigitAt:6] + [code intForDigitAt:8] + [code intForDigitAt:10]) * 3) % 10)) % 10; return check == val; } case 13: // EAN-13 { int check = [code intForDigitAt:12]; int val = (10 - (([code intForDigitAt:0] + [code intForDigitAt:2] + [code intForDigitAt:4] + [code intForDigitAt:6] + [code intForDigitAt:8] + [code intForDigitAt:10] + ([code intForDigitAt:1] + [code intForDigitAt:3] + [code intForDigitAt:5] + [code intForDigitAt:7] + [code intForDigitAt:9] + [code intForDigitAt:11]) * 3) % 10)) % 10; return check == val; } case 14: // EAN-14 { int check = [code intForDigitAt:13]; int val = (10 - (([code intForDigitAt:1] + [code intForDigitAt:3] + [code intForDigitAt:5] + [code intForDigitAt:7] + [code intForDigitAt:9] + [code intForDigitAt:11] + ([code intForDigitAt:0] + [code intForDigitAt:2] + [code intForDigitAt:4] + [code intForDigitAt:6] + [code intForDigitAt:8] + [code intForDigitAt:10] + [code intForDigitAt:12]) * 3) % 10)) % 10; return check == val; } default: return NO; } } 

This uses the category method that I added to NSString :

 - (int)intForDigitAt:(NSUInteger)index { unichar ch = [self characterAtIndex:index]; if (ch >= '0' && ch <= '9') { return ch - '0'; } else return 0; } 

Answer 2

There is no objective-c format or a way to do this, you will need to implement a function that will:

a) Check the number of digits b) Check the digit of the checksum