C#基礎 字符串與數組

第十一講：字符串
一、string是一種特殊的引用類型，使用起來好像值類型
例：class Program
    {
        static void Main(string[] args)
        {
            string s = "123";
            string k = s;
            k = "456";
            Console.WriteLine(s);
        }
    }
結果：123
二、string中部分函數的意思trim除去空格 ToUpper把字母轉換爲大寫 Split分割
例：class Program
    {
        static void Main(string[] args)
        {
            string str = "    123456";
            Console.WriteLine(str);
            Console.WriteLine(str.Trim());
        }
    }
結果：   123456
     123456
第十二講：數組
一、Array:在.NET中全部的數組都是繼承在Array下的，是引用類型，不可以直接定義。實例化的時候不能夠用new關鍵字。屬於抽象類，能夠被子類實例化。
例：static void Main(string[] args)
        {
            Array arr = Array.CreateInstance(typeof(int), 10);
            for (int i = 0; i < 10; i++)
            {
                arr.SetValue(i * 2, i);
            }
            foreach (int i in arr)
            {
                Console.WriteLine(i);
            }
            for (int i = 0; i < 10; i++)
            {
                Console.WriteLine(arr.GetValue(i));
            }
        }
二、一維數組：int[] arrint=new int[10]
（1）Array方法有Sort排序
例：class Program
    {
        static void Main(string[] args)
        {
            int[] arri = new int[] { 2, 35, 1, 3, 53, 216, 1 };
            Array.Sort(arri);
            int len=arri.Length;
            for (int i = 0; i < len; i++)
            {
                Console.WriteLine(arri[i]);
            }
        }
    }
結果：1
      1
      2
      3
      35
      53
      216

（2）Array方法中的Reverse方法表示反轉
例：static void Main(string[] args)
        {
            int[] arri = new int[] { 2, 35, 1, 3, 53, 216, 1 };
            Array.Sort(arri);
            Array.Reverse(arri);
            int len=arri.Length;
            for (int i = 0; i < len; i++)
            {
                Console.WriteLine(arri[i]);
            }
        }
結果：216
      53
      35
      3
      2
      1
      1
三、二維數組定義：int[,] arri=new int[i,j];
int[,] arri = new int[,] { { 1, 2, 3, 4 }, { 5, 6, 7, 8 } };
例：int[,] arri = new int[,] { { 1, 2, 3, 4 }, { 5, 6, 7, 8 } };
            for (int r = 0; r < 2; r++)
            {
                for (int c = 0; c < 4; c++)
                {
                    Console.WriteLine(arri[r,c]);
                }
            }
四、交錯數組：數組中的數組 定義：int[][] arri=new int[2][];不容許有第二個方括號的值的不容許有列
例： int[][] arri = new int[3][];
            arri[0] = new int[] { 1, 2 };
            arri[1] = new int[] { 3};
            arri[2]=new int[]{4,5,6};
            int rlen = arri.Length;
            for (int i = 0; i < rlen; i++)
            {
                int clen = arri[i].Length;
                for (int j = 0; j < clen; j++)
                {
                    Console.WriteLine(arri[i][j]);
                }
            }
            //foreach (int[] i in arri)
            //{
            //    foreach (int j in i)
            //    {
            //        Console.WriteLine(j);
            //    }
            //}
foreach和for循環的結果同樣都爲：
1
2
3
4
5
6
也能夠打印單個元素：Console.WriteLine(arri[2][2]);打印結果爲6.
五、用數組寫學生管理系統
例：namespace Chapter12Demo2
{
    class Program
    {
        static void Main(string[] args)
        {
            string [,] arri=new string[3,3];
            for (int i = 0; i < 3; i++)
            {
                for (int j = 0; j < 3; j++)
                {
                    if (j == 0)
                    {
                        Console.WriteLine("請輸入學生的姓名：");
                       arri[i,j] = Console.ReadLine();
                    }
                    else if (j == 1)
                    {
                        Console.WriteLine("請輸入年齡：");
                        arri[i,j] = Console.ReadLine();
                    }
                    else
                    {
                        Console.WriteLine("請輸入性別：");
                        arri[i,j] = Console.ReadLine();
                    }
                }

 }
           
            for (int i = 0; i <3; i++)
            {
                for (int j = 0; j <3; j++)
                {
                    Console.Write(arri[i,j]);
                }
                Console.WriteLine();
            }
        }
    }
}