2 - Sum of digit recursion in c sharp

Sum of digit recursion in c#

 public string SumOfDigitWithRecursion(int num)

       {

           int sum = 0, r;

           sum = getSumFromRecursion(num);

           return string.Format("Sum of digits
of number:{0}", sum);

       }

       int getSumFromRecursion(int num) {

           if (num == 0)

               return 0;

           return (num % 10
+ getSumFromRecursion(num / 10));

       }

   [TestMethod]

       public void TestSumOfDigitUsingRecursion()

       {

           BasicProgramming basicProgramming
= new BasicProgramming();

           string output = basicProgramming
.SumOfDigitWithRecursion(123);

           Assert.AreEqual("Sum of digits of
number:6", output);

       }

How to find sum of digit using recursion
using dry run method

Step by step process for better understanding
of how the algorithm works.
Let number be 12345.
Step 1-> 12345 % 10 which is equal-too 5 +
( send 12345/10 to next step )

Step 2-> 1234 % 10 which is equal-too 4 +
( send 1234/10 to next step )

Step 3-> 123 % 10 which is equal-too 3 +
( send 123/10 to next step )

Step 4-> 12 % 10 which is equal-too 2 +
( send 12/10 to next step )

Step 5-> 1 % 10 which is equal-too 1 +
( send 1/10 to next step )

Step 6-> 0 algorithm stops

following diagram will illustrate the process of recursion

1 2 3 4 5 6 7 8 9 10 11

public string SumOfDigitWithRecursion(int num) { int sum = 0, r; sum = getSumFromRecursion(num); return string.Format("Sum of digits of number:{0}", sum); } int getSumFromRecursion(int num) { if (num == 0) return 0; return (num % 10 + getSumFromRecursion(num / 10)); }