前言：最近項目比較忙，完全沒有時間寫下總結筆記，今天抽出時間來寫下筆記，供寫後臺的你來做數據處理後臺代碼編寫的參考。

一、分組

   var GroupForList = numberList.GroupBy(x => x).ToDictionary(a => a.Key, b => b.ToList()).ToList();

二、交集、並集、差集

private static List<int> numberList = new List<int>() { 4,5,6,8,9,11 };
private
 
 static List<int> numberListTwo = new List<int>() { 4,5,7,15,16,12 };
public static void Main(string[] args)
 {
            var intersectList = numberList.Intersect(numberListTwo);  //交集
            var str = "";
            var str2 = "";
            var str3 = "";
            foreach
 
 (var item in intersectList)
            {
                str += item+",";
            }
            var exceptList = numberList.Except(numberListTwo);  //差集
            foreach (var item in intersectList)
            {
                str2 += item + ",";
            }
            var unionList = numberList.Union(numberListTwo);   //
 
並集
            foreach (var item in unionList)
            {
                str3 += item + ",";
            }
            Console.WriteLine("交集：" + str);
            Console.WriteLine("差集：" + str2);
            Console.WriteLine("並集：" + str3);

}

三、遞歸

public static void Main(string[] args)
 {
        Recursion(1);
 }
static int i = 0;
private static void Recursion(int number) {
      Console.Write(number+",");
       var newnumber = number + i;
       i++;
       Thread.Sleep(1000);  
       Recursion(newnumber);
 }

結語：這些就是用最簡單的方法展示 各種後臺數據處理時候可能要用到的方法啦。希望能幫助到初學者的你們

c#數據處理總結(分組、交並差與遞歸)