泛型类型排序的一种尝试

   今天复习《Data Structures and Algorithms using C#》的时候，想把书中的第三章的基础排序改为泛型版本。起初想得很简单，将int改为T即可，呵呵，结果发现T是不能直接比较的。然后，用了一下午和一晚上的时间才勉强实现。期间尝试了很多种不同的实现方法，最先想到的是用IComparer接口，通过传递接口来实现。但是有个很大的问题，静态类是不支持继承接口的，而我又不想改变开始的想法。所以想了很久，才使用委托方法做了一次尝试。

具体代码如下：

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namespace ExercisesThree {     public static class BasicSort     {         public delegate bool GreaterThanHandler<T>(T first,T second);           public static void BubbleSort<T>(ref T[] arr,GreaterThanHandler<T> greaterThan)         {             int upper = arr.Length;             int outer = 0, inner = 0, index = 0;             bool exchange = true;             while (exchange && outer < upper)             {                 exchange = false;                 inner = index;                 while (inner < upper-outer-1)                 {                     if (greaterThan(arr[inner],arr[inner + 1]))                     {                         Swap<T>(ref arr[inner],ref arr[inner + 1]);                         exchange = true;                     }                     inner++;                     if (!exchange && greaterThan(arr[inner + 1],arr[inner]))                         index++;                 }                 outer++;             }         }           public static void BubbleSort2<T>(ref T[] arr, GreaterThanHandler<T> greaterThan)         {             int upper = arr.Length-1;             for (int outer = upper; outer >=1 ; outer--)             {                 for (int inner = 0; inner <= outer-1; inner++)                 {                     if(greaterThan(arr[inner],arr[inner+1]))                         Swap<T>(ref arr[inner],ref arr[inner+1]);                 }             }         }           public static void SelectionSort<T>(ref T[] arr, GreaterThanHandler<T> greaterThan)         {             int upper = arr.Length;             int min;             for (int outer = 0; outer < upper; outer++)             {                 min = outer;                 for (int inner = outer; inner < upper; inner++)                 {                     if (greaterThan(arr[min], arr[inner]))                     {                         min = inner;                     }                 }                 if (min != outer)                     Swap<T>(ref arr[outer], ref arr[min]);             }         }           public static void InsertionSort<T>(ref T[] arr,GreaterThanHandler<T> greaterThan)         {             int inner,upper = arr.Length;             T tmp;             for (int outer = 1; outer < upper; outer++)             {                 tmp = arr[outer];                 inner = outer;                 while (inner > 0 &&  greaterThan(arr[inner - 1],tmp))                 {                     arr[inner] = arr[inner - 1];                     inner--;                 }                 arr[inner] = tmp;             }         }           private static void Swap<T>(ref T val1, ref T val2)         {             T tmp = val1;             val1 = val2;             val2 = tmp;         }           //public static bool Compare<T>(ref T val1,ref T val2)         //{         //    return true;         //}     } }

测试代码：

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namespace ExercisesThree {     class Program     {         static void Main(string[] args)         {             int n = 10;             int[] arr = new int[n];             arr = GetArray(n);             DisplayArray(arr);            // BasicSort.BubbleSort<int>(ref arr, GreaterThan);            // BasicSort.SelectionSort<int>(ref arr, GreaterThan);             BasicSort.InsertionSort2<int>(ref arr, GreaterThan);             Console.WriteLine();             DisplayArray(arr);             Console.Read();             //BasicSort.BubbleSort();         }           static int[] GetArray(int n)         {             int[] arr = new int[n];             Random rnd = new Random();             for (int i = 0; i < 10; i++)             {                 arr[i] = rnd.Next(0, 100);             }             return arr;         }           static void DisplayArray(int[] arr)         {                 int upper=arr.Length;                 for (int i = 0; i < upper; i++)                 {                     Console.Write(arr[i] + " ");                 }         }           private static bool GreaterThan(int i1, int i2)         {             return (i1 > i2);         }     } }

   没什么好总结的，哎。C#有很多东西我还不会。有的东西仅仅是有个印象而已，路还很长，要一直下去才行。