Sha256: 37de25f04a5100e25fd689f58e1645911903c6f609aade3b28e96a21eee9732f
Contents?: true
Size: 1.54 KB
Versions: 64
Compression:
Stored size: 1.54 KB
Contents
using System;
using System.Linq;
public class Luhn
{
private readonly long number;
public long CheckDigit { get { return number % 10; } }
public int[] Addends { get; private set; }
public int Checksum { get { return Addends.Sum(); } }
public bool Valid { get { return Checksum % 10 == 0; } }
public Luhn(long number)
{
this.number = number;
Addends = GenerateAddends();
}
private int[] GenerateAddends()
{
var reversedIntArray = SplitToReversedIntArray(number);
for (int i = 1; i < reversedIntArray.Length; i++)
{
if (i % 2 != 0)
reversedIntArray[i] = ConvertDigitForAddend(reversedIntArray[i]);
}
Array.Reverse(reversedIntArray);
return reversedIntArray;
}
private static int[] SplitToReversedIntArray(long value)
{
return value.ToString().Select(c => int.Parse(c.ToString())).Reverse().ToArray();
}
private static int ConvertDigitForAddend(int value)
{
var doubled = value * 2;
return doubled < 10 ? doubled : doubled - 9;
}
public static long Create(long number)
{
var zeroCheckDigitNumber = number * 10;
var luhn = new Luhn(zeroCheckDigitNumber);
if (luhn.Valid)
return zeroCheckDigitNumber;
return zeroCheckDigitNumber + CreateCheckDigit(luhn.Checksum);
}
private static int CreateCheckDigit(int value)
{
var nearestTen = (int)(Math.Ceiling(value / 10.0m) * 10);
return nearestTen - value;
}
}
Version data entries
64 entries across 64 versions & 1 rubygems