Csahrp_Tuple tuple

 Tuple is a new data structure type added after C# 7.1 that
can be used to represent a composite data type (a bit like the composition pattern in design patterns)
 . The first time I knew the word tuple was in Python, and now in C# It is also convenient to use this data type in
Java, just like java also supports the var keyword. Each programming language is gradually moving closer, absorbing the advantages of each other.
We should also use the code flexibly to exert the power of the code.

            Use of region Tuple and ValueTuple   

//Create a Tuple (it can be found that Tuple can hold 1-n data           
            Tuple<int, string, bool> tuple = new Tuple<int, string, bool>(10, "hello", true);
            //Get the components of Tuple (each item will be encapsulated as an attribute of Item (only get method), so it can only be assigned at initialization
            int a = tuple.Item1;
            string b = tuple.Item2;
            bool c = tuple.Item3;
            //You can create an array of Tuples (and can be nested
            Tuple<int, string>[] tuples = new Tuple<int, string>[] { new Tuple<int, string>(100, "s"), new Tuple<int, string>(1000, "sss") };

           

//ValueTuple is an enhanced version of Tuple, with an empty structure, and each item can be assigned a value
            ValueTuple<int, string, bool> vaa = new ValueTuple<int, string, bool>();
            vaa.Item1 = 10;
            vaa.Item2 = "Hello World";
            vaa.Item3 = true;
            
            //Tuple and ValueTuple are also useful when returning multiple values, see the following example for details

 method returns multiple values
         

//ValueTuple is an enhanced version of Tuple, with an empty structure, and each item can be assigned a value
            ValueTuple<int, string, bool> vaa = new ValueTuple<int, string, bool>();
            vaa.Item1 = 10;
            vaa.Item2 = "Hello World";
            vaa.Item3 = true;
            
            //Tuple and ValueTuple are also useful when returning multiple values, see the following example for details

         

  //1. Use the out parameter to return multiple values
            //---------The variables of out parameters need to be declared externally, and there is no unified management for out parameters
            int bb = 0, cc = 0;
            int aa = GetY(1, out bb,out cc);
            Console.WriteLine("aa={0} bb={1} cc={2}",aa,bb,cc);


            //2. Use Tuple to return multiple values
            //------------- There is no array out of bounds, no forced conversion, no external variables, but the name of the Item cannot be customized
            var va = GetZ ();
            int data_aa = va.Item1;
            string data_bb = va.Item2;
            bool data_cc = va.Item3;
            Console.WriteLine("data_aa={0} data_bb={1} data_cc={2}", data_aa, data_bb, data_cc);


            //3. Use ValueTuple to return multiple values
            //--------No external variables are required, there is no array out of bounds, data can be accessed in a custom way instead of Item, no forced conversion is required
            //----- encapsulating it into an object is the best choice
            var vall = Get(1, "Ai");
            Console.WriteLine("id={0}\tname={1}\tpass={2}",vall.id,vall.name,vall.isPass);
           

 return multiple values_method declaration
       

//array returns multiple values
        static object[] GetX()
        {
            return new object[] { 1, "Hi", true };
        }
        //out returns multiple values
        static int GetY(int cc,out int a,out int b)
        {
            a = 10;
            b = 20;
            return cc;
        }
        //Tuple returns multiple values
        static Tuple<int,string,bool> GetZ()
        {
            return new Tuple<int, string, bool>(10, "hi_tuple", false);
        }


        //valueTuple returns multiple values
        static (int id,string name,bool isPass) Get(int a, string b)
        {
           
            return (a,b,true);
        }