Counting repeating numbers in an Array

Question

Fairly new to C#. Have an assignment for class that asks us to generate an array from user inputted values. This part is done and work\'s perfectly.

Now that the arr

Answer 1

foreach (int item in array)
{
     Console.Write(item.ToString() + " ");
     int frequency = 0;
     for (int i = 0; i < array.Length; ++i)
     {
         if (array[i] == item) ++frequency;
     }
     Console.WriteLine(frequency.ToString());
}

A dirty and brute force way. Considering your array is an "int" array. Otherwise, just change the types.

Answer 2

You can create a dictionary in that the keys are numbers, and the values are counts of that specific number in the array, and then increase the values in the dictionary each time a number is found:

Example:

        int[] arrayOfNumbers = new int[] { 1, 4, 2, 7, 2, 6, 4, 4, };
        Dictionary<int, int> countOfItems = new Dictionary<int, int>();
        foreach (int eachNumber in arrayOfNumbers)
        {
            if (countOfItems.ContainsKey(eachNumber))
                countOfItems[eachNumber]++;
            else
                countOfItems[eachNumber] = 1;
        }

This code works in all C# versions, but if you are using C# 3 or greater you could use LINQ, as others are suggesting. =)

Answer 3

You can use LINQ Distinct() extension method.

http://msdn.microsoft.com/en-us/library/system.linq.enumerable.distinct.aspx

Answer 4

Are you allow to use LINQ? If so, investigate GroupBy and Count(). Basically there's a one-liner which will work here, but as it's homework I'll let you work out the details for yourself... ask for more help when you've had a go though, if you run into problems.

Answer 5

Without LINQ, you could keep track of the numbers you're generating. A data structure like a Dictionary could work well, mapping the numbers to how many times you've seen them so far.