c# ValueTuple

为什么我们需要 ValueTuple？

• Tuple 是引用类型，但 ValueTuple 是值类型。
• Tuple 不提供命名约定，但 ValueTuple 提供了强大的命名约定。
• 在 Tuples 中，您不能创建零分量的元组，但在 ValueTuple 中，您可以创建零元素的元组。
• ValueTuple 的性能优于 Tuple。 因为 ValueTuple 提供了一种轻量级的机制，用于从现有方法返回多个值。 并且 ValueTuple 的语法比 Tuples 更优化。
• ValueTuple 通过使用解构和 _ 关键字为访问值元组的元素提供了更大的灵活性。 但是 Tuple 不能提供解构的概念和 _ 关键字。
• 在 ValueTuple 中，item1 和 item2 等成员是字段。 但在元组中，它们是属性。
• 在 ValueTuple 中，字段是可变的。 但是在元组中，字段是只读的。

Creating a ValueTuple

• Using Constructor

  // Constructor for creating one element
  ValueTuple(T1)
  // Constructor for creating two elements
  ValueTuple<T1, T2>(T1, T2)
  // Constructor for creating eight elements
  ValueTuple<T1, T2, T3, T4, T5, T6, T7, TRest>(T1, T2, T3, T4, T5, T6, T7, TRest) /

Sample

using System;
 
class GFG {
 
    // Main method
    static public void Main()
    {
 
        // ValueTuple with one element
        ValueTuple<int> ValTpl1 = new ValueTuple<int>(345678);
 
        // ValueTuple with three elements
        ValueTuple<string, string, int> ValTpl2 = new ValueTuple<string,
                                        string, int>("C#", "Java", 586);
 
        // ValueTuple with eight elements
        ValueTuple<int, int, int, int, int, int, int, ValueTuple<int> > ValTpl3 = new ValueTuple<int,
                                  int, int, int, int, int, int, ValueTuple<int> >(45, 67, 65, 34, 34,
                                                                    34, 23, new ValueTuple<int>(90));
    }
}

• Using Create Method

// Method for creating an empty value tuple
Create();
// Method for creating 1-ValueTuple
Create(T1)
// Method for creating 8-ValueTuple
Create<T1, T2, T3, T4, T5, T6, T7, TRest>(T1, T2, T3, T4, T5, T6, T7, T8)

Sample

using System;
 
public class GFG {
 
    // Main method
    static public void Main()
    {
 
        // Creating 0-ValueTuple
        // Using Create() Method
        var Valtpl1 = ValueTuple.Create();
 
        // Creating 3-ValueTuple
        // Using Create(T1, T2, T3) Method
        var Valtpl2 = ValueTuple.Create(12, 30, 40, 50);
 
        // Creating 8-ValueTuple
        // Using Create(T1, T2, T3, T4, T5, T6, T7, T8) Method
        var Valtpl3 = ValueTuple.Create(34, "GeeksforGeeks",
                      'g', 'f', 'g', 56.78, 4323, "geeks");
    }
}

• Using parenthesis()

named member

using System;
 
public class GFG {
    static public void Main()
    {
        (int age, string Aname, string Lang) author = (23, "Sonia", "C#");
    }
}

using System;
 
public class GFG {
 
    static public void Main()
    {
        var author = (age : 23, Aname
                      : "Sonia", Lang
                      : "C#");
    }
}

UnNamed Member

using System;
 
public class GFG {
    static public void Main()
    {
        var author = (20, "Siya", "Ruby");
    }
}

using System;
 
public class GFG {
    static public void Main()
    {
        ValueTuple<int, string, string> author = (20, "Siya", "Ruby");
    }
}

Accessing ValueTuple members

• Accessing unnamed members

using System;
 
public class GFG {
 
    // Main Method
    static public void Main()
    {
 
        // ValueTuple with three elements
        var author = (20, "Siya", "Ruby");
 
        // Accessing the ValueTuple
        // Using default Item property
        Console.WriteLine("Age:" + author.Item1);
        Console.WriteLine("Name:" + author.Item2);
        Console.WriteLine("Language:" + author.Item3);
    }
}

• Accessing Named members:

using System;
 
public class GFG {
 
    // Main Method
    static public void Main()
    {
 
        // ValueTuple with three elements
        var library = (Book_id : 2340, Author_name
                       : "Arundhati Roy", Book_name
                       : "The God of Small Things");
 
        // Accessing the ValueTuple
        // according to their names
        Console.WriteLine("Book Id: {0}", library.Book_id);
        Console.WriteLine("Author Name: {0}", library.Author_name);
        Console.WriteLine("Book Name: {0}", library.Book_name);
    }
}

Returning ValueTuple

using System;
 
public class GFG {
 
    // This method returns the tourist details
    static(int, string, string) TouristDetails()
    {
        return (384645, "Sophite", "USA");
    }
 
    // Main method
    static public void Main()
    {
 
        // Store the data provided by the TouristDetails method
        var(Tourist_Id, Tourist_Name, Country) = TouristDetails();
 
        // Display data
        Console.WriteLine("Tourist Details: ");
        Console.WriteLine($ "Tourist Id: {Tourist_Id}");
        Console.WriteLine($ "Tourist Name: {Tourist_Name}");
        Console.WriteLine($ "Country: {Country}");
    }
}