generate random numbers with no repeat in c#

Question

How can I generate random numbers with no repeat in C#. I have one array and I want to fill every room with random numbers from 0 to 9. Each room shoud have diffrent numbers. I use this:

for (int i = 0; i < 20; i++)
{
    Random rnd = new Random();
    int temp = 0;
    temp = rnd.Next(0, 9);
    page[i] = temp;
}

But I get same number in evey room's of array.

Solution 1

With such a small list of numbers to choose from you can simply generate a list that contains all of them and then shuffle them.

Solution 2

Your problem is that you are creating the Random object in every loop. The Random object must be created only once. Try this instead:

Random rnd = new Random(); // <-- This line goes out of the loop        
for (int i = 0; i < 20; i++) {
    int temp = 0;
    temp = rnd.Next(0, 9);
    page[i] = temp;
}

Comments

[Security Hound]

"I just want to know how i can generate random numbers with no repeat in c#?" - This is not possible. A random number is suppose to repeat otherwise its not actually a random number generator but a unique value generator which is trival to code. Your code is also flawed because you will always have the same seed value.

[Werner Henze]

You talk about rooms but have a page array!? Do you mean every entry in array page shall be unique? Do I understand you right that you want 20 digits in page, all being distinct?

[Admin]

Also this is not at all efficient for large array instead you may create a sorted array and use one shuffling techniques to create the randomness

[Benvorth]

Can you explain your answer a bit more?