C#

Collection coll=new Collection(holding all elements);   // order doesn't matter
int n=coll.Count;
for(int i=n; i>0; i--) {
     int j=RandomGenerator.Next(0, i);       // j is in range [0, i) which shrinks all the time
     int pick=coll[j];  // your current pick
     coll.RemoveAt(j);  // now remove it
}

int maxSize = 10;                
char[] chars = new char[62];
string a;
a = "1234567890";
chars = a.ToCharArray();
int size = maxSize;
byte[] data = new byte[1];
RNGCryptoServiceProvider crypto = new RNGCryptoServiceProvider();
crypto.GetNonZeroBytes(data);
size = maxSize;
data = new byte[size];
crypto.GetNonZeroBytes(data);
StringBuilder resultUID = new StringBuilder(size);
foreach (byte b in data)
{
   resultUID.Append(chars[b % (chars.Length - 1)]);
}
string generatedNumber = resultUID.ToString(); 

Random rnd = new Random(seed);
int num=rnd.Next(1,10);

private static void NonRecurrentRandomize(int capacity)
{
    //initialize sample:
    //capacity is your sample size
    List<int> orderedList = new List<int>(capacity);
    for (int i = 0; i < capacity; i++)
    {
        orderedList.Add(i); //0,1,2,3,4,..
    }

    Random r = new Random();
    //Begin process:
    while (orderedList.Count > 0)
    {
        int popIndex = r.Next(0, orderedList.Count);
        //this is the item in turn:
        Console.WriteLine(orderedList[popIndex]);
        orderedList.RemoveAt(popIndex);
    }
}

HashSet<int> hash = new HashSet<int>();
Random random = new Random(DateTime.Now.Milliseconds);
int value = 0;
int final = 0;
do
{
    try
    {
        if (hash.Count == 9)
        {
            final++;
            hash.Add(final);
        }
        value = random.Next(1, 10);
        hash.Add(value);
    }
    catch (Exception)
    {
        // eat the exception
    }
}
while (hash.Count < 10)

TestHashSet() completed in
        00:00:00.0380860
TestList() completed in
        00:00:00.0009766

HashSet<int> hash   = new HashSet<int>();
Random       random = new Random(DateTime.Now.Millisecond);
int          value  = 0;
int          start  = 1;
int          stop   = 10;
do
{
    try
    {
        value = random.Next(start, stop);
        hash.Add(value);
        if (value == start)
        {
            start++;
        }
        else if (value == stop)
        {
            stop--;
        }
        if (start == stop && hash.Count < 10)
        {
            hash.Add(start);
        }
    }
    catch (Exception)
    {
        // eat the exception
    }
} while (hash.Count < 10);

meet_ssr wrote:

Performance is a concern

meeram395 wrote:

I have a C# mobile application class.

MSDN[^] states:

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role not supported), Windows Server 2003 SP2

I are Troll