I am trying to iterate through some number as 02100021, this is a routing number which needs to get validated if it is a proper routing number. Therefore I am using the ABA routing number validation check as 3*(d1+d4+d7) + 7*(d2+d5+d8) + (d3+d6+d9) where mod 10 = 0
Since I have the number in integer type, my first question is how can I iterate through such number with 0's in it, or if there is some easier way of iterating through mode and multiplying it with such number.
Thanks
If I understand correctly, 7 * (d2, d5, d8) should be 7 * (d2 + d5 + d8). Zeros modulo 10 do not count.
bool correct(long x) { long a = x / 10 + x / 10000 + x / 10000000L; long b = x / 100 + x / 100000L + x / 100000000L; long c = x / 1000 + x / 1000000L + x / 1000000000L; int aba_checksum = (int)((3 * a + 7 * b + c) % 10); return aba_checksum == 0; } Corrected for d[i] = digit * 10 ^ (9 - i)
bool correct(long x) { long a = x / 100000000L + x / 100000L + x / 100; long b = x / 10000000L + x / 10000L + x / 10; long c = x / 1000000L + x / 1000L + x; int aba_checksum = (int)((3 * a + 7 * b + c) % 10); return aba_checksum == 0; } Modulo arithmetic can be done at the end. To prevent overflow (to negative numbers) one might do it earlier, above even 7 * b does not overflow.
(x/decimal_place) % 10 would fix that I believe. -- Untested.
x / 1000 + x / 1000000L + x / 1000000000L does not give you the sum of digits 3, 6 and 9. For x=123456789 it gives 123456+123+0=123579, not 3+6+9=18.
