random number generator without duplicates c#
using System.Linq;
public int range;
public int MyNum[];
public int KnownNumbers[];
public int UniqueNumbers;
private void MyNumbers()
    {
    MyNum = new int[range];
    for (int i = 0; i < range; i++)
    {
        MyNum[i] = i;
    }
}
private void RandomDiffNumber()
{
    KnownNumbers = new int[UniqueNumbers];
    int Cmax = MyNum.Length;
    for (int i = 0; i < UniqueNumbers; i++)
    {
        Cmax = MyNum.Length;
        int rand = Random.Range(0,Cmax);
        KnownNumbers[i] = MyNum[rand];
        MyNum = MyNum.Where((source, index) => index != rand).ToArray();
    }
    // Now KnownNumbers contain unique Random Numbers
}