Functional way to check if array of numbers is sequential

Question

Let\'s say that an array is sequential when each successful element has the value of previous element + 1. Suppose I have an array of numbers like {5,6,7,

Answer 1

This should do the trick, for all sequential, non sequential data. A complete example with sample input. Tested and works fine

var list = new List(new[] { 7, 6, 5, 4, 3,9});
int minValue = list.Min();
int maxValue = list.Count;
List test =  Enumerable.Range(minValue, maxValue).ToList();
var result = Enumerable.Range(minValue, maxValue).Except(list);
if (result.ToList().Count == 0)
{
  Console.WriteLine("numbers are in sequence");
}
else
{               
   Console.WriteLine("Numbers are not in sequence");
 }