Luhn Algorithm | C#

March 19th, 2021 01:21:32 AM

					
// C# program to implement // Luhn algorithm using System; class GFG { // Returns true if given // card number is valid static bool checkLuhn(String cardNo) { int nDigits = cardNo.Length; int nSum = 0; bool isSecond = false; for (int i = nDigits - 1; i >= 0; i--) { int d = cardNo[i] - '0'; if (isSecond == true) d = d * 2; // We add two digits to handle // cases that make two digits // after doubling nSum += d / 10; nSum += d % 10; isSecond = !isSecond; } return (nSum % 10 == 0); } // Driver code static public void Main() { String cardNo = "79927398713"; if (checkLuhn(cardNo)) Console.WriteLine("This is a valid card"); else Console.WriteLine("This is not a valid card"); } }

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