Generic Methods

Avuya Mxoli

Hi All,

I just started learning generics and we were asked to create a generic method in a class that accepts an array and an individual object of the same type. The method should remove duplicates in the array and replace the duplicate with a with a default or elimination value represented by the second parameter. We then have to create an application that will implement this using 3 different types that have different lengths.
I've seen many ways of doing this but since I am still very new at this I don't know which one to apply to my problem. Any help will be appreciated.

4 Replies

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Vulpes14y ago
Accepted answer
This is how I'd do it, though I've just done it for one type - I'll leave you to do it for two other types:

using System;
using System.Collections.Generic;

class Program
{
static void Main()
{
MyClass mc = new MyClass();
int[] ia = {1, 1, 3, 4, 4, 6, 1, 7, 3, 8};
mc.MyMethod(ia, 2); // use 2 as default value
// check it worked
foreach(int i in ia) Console.Write("{0} ", i);
Console.WriteLine();
Console.ReadKey();
}
}

class MyClass
{
public void MyMethod(T[] arr, T defValue)
{
if (arr == null || arr.Length <= 1) return;

List dupList = new List();

// find indices of all duplicates
for(int i = 1; i < arr.Length; i++)
{
if(Array.IndexOf(arr, arr[i], 0, i) > -1) dupList.Add(i);
}

// if there are any duplicates replace them with default value
if (dupList.Count == 0) return;

for(int i = 0; i < dupList.Count; i++)
{
arr[dupList[i]] = defValue;
}
}
}

As expected, the output is:

1 2 3 4 2 6 2 7 2 8

Notice that there's no need to specify 'int' as the type parameter when you call MyMethod because the compiler can infer this from the types of the arguments.
Vulpes14y ago
Yes, you could eliminate that line.

In fact, if you don't need to know which items are duplicates, you could simplify the whole method to just this:

public void MyMethod(T[] arr, T defValue)
{
if (arr == null || arr.Length <= 1) return;

for(int i = 1; i < arr.Length; i++)
{
if(Array.IndexOf(arr, arr[i], 0, i) > -1) arr[i] = defValue;
}
}
theLizard14y ago
// if there are any duplicates replace them with default value
if (dupList.Count == 0) return;

for(int i = 0; i < dupList.Count; i++)
{
arr[dupList[i]] = defValue;
}

No need to do this if (dupList.Count == 0) return; because if dupList count is 0 then it will fall through the loop test
Avuya Mxoli14y ago
Thank you so much Vulpes that helped me alot!!