Question

Let’s say we have this numbers 51,53,58,60,78. How can we select a number randomly in such a way if its already selected/picked, it will not be selected in the next run.

Also, after all numbers are selected, everything is restarted and the process repeats itself.

Answer 1

Load your integers into an array. Create an instance of the Random class. Call the Random.Next(int minValue, int maxValue) method with 0 being the minValue, and your array count minus 1 being your maxValue. Then use that random integer to reference your integer array.

Random rnd = new Random();
int nextArrayIndex;
int[] randomNumbers = new int[] {51, 53, 58, 60, 78};

nextArrayIndex = rnd.Next(0, randomNumbers.Count() - 1);

Console.Writeline("Random Value: {0}", randomNumbers[nextArrayIndex].ToString());

Edit: for non repeating data, just store the index that was already use of the integer array in a separate list and prior to utilizing the random number, do a check on the list to see if it was already used. If so, then re-run the random number code. If it is full, then don’t allow that to continue in an endless loop.