Question

I have two arrays:

 string[] array1 = {"a","b","c","d","e"}

 string[] array1 = {"x","y","a","b","a"}

I want to print the result like this:

a = 3
b = 2
c = 1
d = 1
e = 1
x = 1
y = 1
z = 1

I can run a loop inside the loop and find this out but is there a better way to achieve the same result?

I want to do this in plain C# without using LINQ.

Answer 1

You can use LINQ to accomplish this:

var counts = array1.Concat(array2)
                  .GroupBy(v => v)
                  .Select(g => new { Value=g.Key, Number=g.Count() });

foreach(var item in counts.OrderBy(i => i.Value))
    Console.WriteLine("{0} = {1}", item.Value, item.Number);

---

Given that you want to avoid using LINQ and the extension methods for some reason, you could build your own dictionary:

var counts = new Dictionary<string, int>();
foreach(string item in array1)
{
    if (counts.ContainsKey(item))
        counts[item]++;
    else
        counts[item] = 1;
}
foreach(string item in array2)
{
    if (counts.ContainsKey(item))
        counts[item]++;
    else
        counts[item] = 1;
}

// Print out counts
foreach(var kvp in counts)
    Console.WriteLine("{0} = {1}", kvp.Key, kvp.Value);

Note that this doesn’t sort the results – if you need them sorted, you’d have to do that as well.