c#学习笔记1-简单算法

 using System;
 namespace Demo
 {
     class Studycs
     {
         public static void Main(String[] args)
         {
             // String result = Revert("abcdef");
             int[] numbers = { , , , ,  };
             //  int result = searchTree(numbers, 7);

             int[] result=sortSelect(numbers);
             foreach(int item in result)
             {
                 Console.WriteLine(item);
             }
             //  char c ='c';
             //  String result = toCompareChar("aABCDEFghiJKm");

             Console.ReadKey();
         }

         /// <summary>
         /// 翻转字符串
         /// </summary>
         /// <param name="str"></param>
         /// <returns></returns>
         static String Revert(String str)
         {
             String result = String.Empty;
             char[] array = str.ToCharArray();
             for(int i = array.Length - ; i >= ; i--)
             {
                 result += array[i];
             }
             return result;
         }

         /// <summary>
         /// 二分查找
         /// </summary>
         /// <param name="array"></param>
         /// <param name="number"></param>
         /// <returns></returns>
         static int  searchTree(int[] array,int number)
         {
             int min =;
             int max = array.Length-;
             int index =-;
             while (max >= min)
             {
                 int result = (min + max) / ;
                 if (array[result] == number)
                 {
                     index = result;
                     break;
                 }
                 else if (array[result] > number)
                 {
                     max = result - ;
                 }
                 else
                 {
                     min = result + ;
                 }
             }
             return index;

         }

         /// <summary>
         /// 一维数组最大值
         /// </summary>
         /// <param name="array"></param>
         /// <returns></returns>
         static int Max(int[] array)
         {
             int max =array[];
             for(int i = ; i < array.Length; i++)
             {
                 if (array[i] > max) max = array[i];
             }
             return max;
         }

         /// <summary>
         /// 查找数组的下标位置
         /// </summary>
         /// <param name="array"></param>
         /// <param name="n"></param>
         /// <returns></returns>

         static int path(int[] array,int n)
         {
             int result = -;
             for(int i = ; i < array.Length; i++)
             {
                 if (n == array[i]) result = i;
             }
             return result;
         }

         /// <summary>
         /// 查找字符串的下表位置
         /// </summary>
         /// <param name="str"></param>
         /// <param name="c"></param>
         /// <returns></returns>

         static int  searchStr(String str ,char c)
         {
             int result = ;
             char[] array = str.ToCharArray();
             for(int i = ; i < array.Length; i++)
             {
                 if (c == array[i])
                 {
                     result++;
                 }
             }
             return result;
         }

         /// <summary>
         /// 平均数
         /// </summary>
         /// <param name="array"></param>
         /// <returns></returns>

         static Double avg(int[] array)
         {
             Double count=;

             for(int i = ; i < array.Length; i++)
             {
                 count += array[i];
             }

             return count / array.Length;
         }

         /// <summary>
         /// 选择排序
         /// </summary>
         /// <param name="array"></param>
         /// <returns></returns>
         static int[] sortSelect(int[] array)
         {
             for(int i =; i < array.Length - ; i++)
             {
                 for(int j=i+; j < array.Length; j++)
                 {
                     if (array[i] > array[j])
                     {
                         int temp = array[i];
                         array[i] = array[j];
                         array[j] = temp;
                     }
                 }
             }
             return array;
         }

         /// <summary>
         /// 大小写字符转换
         /// </summary>
         /// <param name="str"></param>
         /// <returns></returns>
         static String toCompareChar(String str)
         {
             String result ="";
             char[] array = str.ToCharArray();
             for(int i=; i < array.Length; i++)
             {
                 if(array[i]>='A' && array[i] <= 'Z')
                 {
                     result += Convert.ToChar(array[i] + );
                 }
                 if (array[i] >= 'a' && array[i] <= 'z')
                 {
                     result += Convert.ToChar(array[i] -);
                 }
             }
             return result;

         }
     }
 }