Binary Search generic array - CSharp System

CSharp examples for System:Array Search

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Description

Binary Search generic array

Demo Code

// Apache License 2.0 (Apache)
using System;//from  w w  w .j  a  v  a 2 s.  co m

public class Main{

        // This function is called when the user doesn't specify any comparer.
        // Since T is constrained here, we can call IComparable<T>.CompareTo here.
        // We can avoid boxing for value type and casting for reference types.
        private static int BinarySearch(T[] array, int index, int length, T value)
        {
            int lo = index;
            int hi = index + length - 1;
            while (lo <= hi)
            {
                int i = lo + ((hi - lo) >> 1);
                int order;
                if (array[i] == null)
                {
                    order = (value == null) ? 0 : -1;
                }
                else
                {
                    order = array[i].CompareTo(value);
                }

                if (order == 0)
                {
                    return i;
                }

                if (order < 0)
                {
                    lo = i + 1;
                }
                else
                {
                    hi = i - 1;
                }
            }

            return ~lo;
        }
        public int BinarySearch(T[] array, int index, int length, T value, IComparer<T> comparer)
        {
            try
            {
                if (comparer == null || comparer == Comparer<T>.Default)
                {
                    return BinarySearch(array, index, length, value);
                }
                else
                {
                    return ArraySortHelper<T>.InternalBinarySearch(array, index, length, value, comparer);
                }
            }
            catch (Exception e)
            {
                throw new InvalidOperationException("InvalidOperation_IComparerFailed");
            }
        }
}

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