var number = new int[10];
for (int i = 0; i < number.Length; i++)
{
Console.Write("Write a number : ");
int x = int.Parse(Console.ReadLine());
if (number.Contains(x))
{
Console.WriteLine("This number already exists");
i--; // retry for this index
}
else
{
number[i] = x;
}
}
Try something like this if you do not want to use a HashSet.
4
solved How do I prevent from writing a number that is already written?