c# - Removing a number, after randomly picking it from a list -

i'm making little bingo game have list of numbers (1-90). have randomly pick number, how remove number after have randomly chosen it?

this attempt far:

public partial class form1 : form {      int r = 0;     public form1()     {         initializecomponent();     }      private void btn_number_click(object sender, eventargs e)     {         random random = new random();         list<int> bingonumbers = new list<int>();          for(int = 0; < 91; i++)         {             bingonumbers.add(i);         }          r = random.next(bingonumbers.count);         bingonumbers.removeat(r);         richtextbox1.text = bingonumbers[r].tostring();         richtextbox2.text = bingonumbers[r].tostring();      } } 

everytime click on button, list gets refilled 90 numbers. guess should contain 1 less number every click, yes?

then need instantiate outside click method.

list<int> bingonumbers = enumerable.range(1, 90).tolist();  private void btn_number_click(object sender, eventargs e) {     int r = bingonumbers.orderby(bn => guid.newguid()).firstordefault();     bingonumbers.remove(r);     richtextbox1.text = bingonumbers[r].tostring();     richtextbox2.text = bingonumbers[r].tostring(); } 

i've removed random variable, , replaced linq magic, orders remaining bingo numbers random factor , takes first argument - , removes it. if bingonumbers empty return 0.

if want implement real shuffling, go fisher-yates-shuffle:

random rnd = new random(); //fisher-yates-shuffle (int x = bingonumbers.count - 1; x > 0; x--) {     int y = rnd.next(x + 1);     //swapping      int temp = bingonumbers[x];     bingonumbers[x] = bingonumbers[y];     bingonumbers[y] = temp; } //take first item out of shuffled list int r = bingonumbers[0]; //remove item bingonumbers.remove(r);