Random Array of numbers

Michael Malcolm

Hi there, I would like to figure out how to shorten a piece of code.
I have it working the way I want it to work however I know it can be simplified, I just can't figure out how.

I want to make a do while loop that checks to see if the array is empty.

int draw;
int[] balls = new int[5];
int size = balls.Length;
int count = 0;

Random rdmn = new Random();

for (int i = 0; i < size; i++)
{

draw = rdmn.Next(50);
if (!balls.Contains(draw))
{
balls[count] = draw;
count++;
}
else
{
size++;
}
}

foreach (int n in balls)
{
Console.WriteLine(n);
}

Right now I am adding to the size of the loop if the number is not unique. However if I can put in a do while loop then I can get rid of int size, etc.

Thank for your time.

4 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes15y ago
Accepted answer
It would be possible to do it like this:

int draw;
int[] balls = new int[5];
int size = balls.Length; // all zero by default
for(int i = 0; i < size; i++) balls[i] = -1;;

Random rdmn = new Random();

for(int i = 0; i < size; i++)
{
while(true)
{
draw = rdmn.Next(50); // random n umber between 0 and 49
if (!balls.Contains(draw))
{
balls[i] = draw;
break;
}
}
}

foreach (int n in balls)
{
Console.WriteLine(n);
}

Notice that you have a small problem at the moment in that all the elements of balls are zero to start with and the random number could conceivably be zero as well. I've fixed it by re-initializing all the elements of the array to -1.
Michael Malcolm15y ago
This has been very helpful thank you very much.
Vulpes15y ago
Yes, when you create an array of ints, then it's automatically filled with zero which is the default value of an int.

Similarly, an array of bools would be filled with 'false', an array of chars with '\0' and an array of strings (or any other reference type) with null.

Incidentally, it's possible to create an empty array by setting its length to 0:

int[] empty = new int[0];

but, remembering, that you can't change an array's length once you've created it, this is only of use in special situations.
Michael Malcolm15y ago
Ah so what you are saying is when I create the array it is automatically filled with zero rather than null.
So if I make the values -1 then I check to see if there is -1 and this would work the same as if array is empty then do.

My understanding of Array's isn't very strong. That is why I asked for help.

I thought that I could:

while (array is empty)

generate random number
if number isn't in the array
add it

Thanks for your time.