二分搜索

internal static int InternalBinarySearch(  
  T[] array,  
  int index,  
  int length,  
  T value,  
  IComparer<T> comparer)  
{  
  int num1 = index;  
  int num2 = index + length - 1;  
  while (num1 <= num2)  
  {    
    int index1 = num1 + (num2 - num1 >> 1);  
    int num3 = comparer.Compare(array[index1], value);  
    if (num3 == 0)  
      return index1;  
    if (num3 < 0)  
      num1 = index1 + 1;  
    else  
      num2 = index1 - 1;  
  }  
  return ~num1;  
}