C# 字元串、數組和List的截取和轉換

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading;

namespace ConsoleApp1
{
    class Program
    {
        /// <summary>
        /// 字元串，數組和List的截取，轉換
        /// </summary>
        /// <param name="args"></param>
        static void Main(string[] args)
        {
            string str = "abcdefghij1234567890";
            int i = 4;
            string str1 = str.Substring(0, i);//截取字元串前i位--abcd
            string str2 = str.Remove(i, str.Length - i);//移除字元串i位後面的字元=截取字元串前i位--abcd
            string str3 = str.Remove(0, i);//截取字元串i位之後的字元串--efghij1234567890
            string str4 = str.Substring(i);//截取字元串i位之後的字元串--efghij1234567890
            string str5 = str.Substring(str.Length - i);//截取字元串後i位--7890
            string str6 = str.Remove(0, str.Length - i);//截取字元串後i位--7890
            string str7 = str.Substring(0, str.Length - i);//去掉字元串後i位--abcdefghij123456
            string str8 = str.Remove(str.Length - i, i);//去掉字元串後i位--abcdefghij123456
            string str9 = str.Replace("abc", "ABC");//替換字元串中的字元串--ABCdefghij1234567890
            string str0 = str.ToUpper();//小寫字母轉換成大寫字母--ABCDEFGHIJ1234567890
            string str10 = str0.ToLower();//大寫字母轉換成小寫字母--abcdefghij1234567890
            string str11= str.Substring(str.Length - 1, 1);//截取字元串最後一位--0
            int m = str.IndexOf("cde") + 1;
            int n = str.IndexOf("23");
            string str12 = str.Substring(m, n - m + 2);//截取從開始字元串到結束字元串範圍--cdefghij123
            string s = "a,b,c,d,e,f,g,h,i,j";
            string[] strArray = s.Split(','); //字元串轉數組
            string str13 = string.Join(",", strArray);//數組轉字元串
            List<string> list = new List<string>(s.Split(','));//字元串轉List
            string str14 = string.Join(",", list.ToArray());//List轉字元串
            string[] str15 = list.ToArray();//List轉數組
            List<string> listS = new List<string>(str15);//數組轉List
            Console.WriteLine(str0);
            Console.WriteLine(str12);
            Console.ReadLine();
        }
    }
    
}