1 - Sum of digit in c sharp

Sum of digit in c#

 public string SumOfDigit(int num) {

  int sum = 0, r;

  while (num > 0)

   {

               r = num % 10;

               num = num / 10;

               sum = sum + r;

     }

           return string.Format("Sum of digits

of number:{0}", sum);

       }

       [TestMethod]

       public void TestSumOfDigit()

       {

       BasicProgramming basicProgramming

= new BasicProgramming();

        string output

= basicProgramming.SumOfDigit(123);

       Assert.AreEqual("Sum of digits of number:6"

, output);

       }

How to find sum digit using dry run method.

For example, if the input is 98, the variable sum is 0 initially
98%10 = 8 (% is modulus operator which gives us
remainder when 98 is divided by 10).

sum = sum + remainder
so sum = 8 now.

98/10 = 9 because in C language whenever we divide
an integer by an another integer we get an integer.
9%10 = 9

sum = 8 (previous value) + 9
sum = 17
9/10 = 0.

So finally n = 0, the loop ends we get the required sum.

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