Tuple in C# 4.0

Tuple provides us with a way to group elements of disparate data types together.This is present in functional languages like Haskell and also dynamic languages like Python.A common example of a tuple is a pair of coordinates defining a point in two dimensional space.In Haskell a tuple storing name and age of person is defined as :

let t = ("Bob",57)

In Python it will look something like:

t = "Bob",57

In C# 4.0 we have a provision to create tuples but the syntax is not as beautiful as it is in Haskell and Python.We have got a set of Tuple classes as shown below which helps us to work with tuples:

• Tuple – This static class provides 8 overloads of Create methods to create tuples of size 1 to 8
  • Create(T1)
  • Create(T1,T2)
  • Create(T1,T2,T3)
  • Create(T1,T2,T3,T4)
  • Create(T1,T2,T3,T4,T5)
  • Create(T1,T2,T3,T4,T5,T6)
  • Create(T1,T2,T3,T4,T5,T6,T7)
  • Create(T1,T2,T3,T4,T5,T6,T7,T8)
• Tuple<T1> – Represents a tuple of size 1
• Tuple<T1,T2> – Represents a tuple of size 2
• Tuple<T1,T2,T3> – Represents a tuple of size 3
• Tuple<T1,T2,T3,T4> – Represents a tuple of size 4
• Tuple<T1,T2,T3,T4,T5> – Represents a tuple of size 5
• Tuple<T1,T2,T3,T4,T5,T6> – Represents a tuple of size 6
• Tuple<T1,T2,T3,T4,T5,T6,T7> – Represents a tuple of size 7
• Tuple<T1,T2,T3,T4,T5,T6,T7,TRest> – Represents a tuple of size 8 or greater.

Consider the following code:

static void Main(string[] args)
{
    var t = Tuple.Create<string, int>("Bob", 57);
    Console.WriteLine(t);
    Console.Read();
} 

It creates a tuple same as what we saw in Haskell/Python samples and the program prints:

(Bob, 57)

We can create nested tuples as shown below:

static void Main(string[] args)
{
    var t = Tuple.Create("Bob", 57,new Tuple<string,string>("California","Los Angeles"));
    Console.WriteLine(t);
    Console.Read();
}  

The program will print out:

(Bob, 57, (California, Los Angeles))

The class Tuple<T1,T2,T3,T4,T5,T6,T7,TRest> creates a Tuple with 8 or more elements whereas method Create(T1,T2,T3,T4,T5,T6,T8)creates a tuple with eight elements.This is clear from the example shown below:

static void Main(string[] args)
{ 

    var t1 = Tuple.Create("Test", 1, 2, 3, 4, 5, 6, 
                          new Tuple<int, int>(7, 8));
    Console.WriteLine("Nested Tuple with 8 elements" + t1); 

    var t2 = new Tuple<string,int,int,int,
                       int,int,int,Tuple<int,int>>
                       ("Test", 1, 2, 3, 4, 5, 6, 
                       new Tuple<int, int>(7, 8)); 

    Console.WriteLine("Tuple with 9 elements" + t2); 

    Console.Read();
} 

The program prints out:

Nested Tuple with 8 elements(Test, 1, 2, 3, 4, 5, 6, (7, 8))
Tuple with 9 elements(Test, 1, 2, 3, 4, 5, 6, 7, 8)

The values stored inside a tuple can be accessed using the ItemN properties as shown below:

static void Main(string[] args)
{
    var t = Tuple.Create("Bob", 57);
    Console.WriteLine("Name:{0},Age:{1}",t.Item1,t.Item2);
    Console.Read();
} 

Here we do not have enumerator to iterate through this because this is not a collection.This is more closer to anonymous class with anonymous properties as well.In pure functional languages like Haskell this can be very helpful in returning multiple values of disparate types from a function.But how come in a language like C# or even python this can be helpful where we have got classes.The answer is, sometimes we create a class just to store some temporary data for programming purpose where the class does not have any meaning.A tuple can be very helpful in such a situation.