Necessary and Sufficient

Question: Write a function to reverse an array in-place in C#.
Answer: Since arrays have direct access via the [] operator it's simple enough to iterate through the array elements and perform a swap. The key things to remember are: (1) you only need to iterate over half of the array; and (2) it's best to write this as a generic function since we make the function more useful.

Note that arrays are reference types in C# so it doesn't matter if you pass the array in by reference or by value, the outcome will be the same if the array is not initially null.

Here's the C# code:

        static void Main()
        {
            var arr = new byte[] {0x04, 0x01, 0x02, 0x06, 0x00};
            ReverseArray(arr);
            foreach(var element in arr)
                Console.WriteLine( element );
        }

        public static void ReverseArray<T>(T[] a)
        {
            int n = a.Length;
            for (int i = 0; i < n/2; i++)
            {
                T t = a[n-i-1];
                a[n-i-1] = a[i];
                a[i] = t;
            }
        }