What is a Tuple?

In mathematics, A Tuple is a sequence of finite length. An n-tuple is a tuple with n elements. For example (2, 4, 3, 8) is a 4-tuple.

C# 4.0 introduced a new data type Tuple. Tuple is not new in software engineering, but of course it is new in .NET framework 4.0. A tuple is a simple generic data structure that holds an ordered set of items of heterogeneous types. There are two ways to instantiate Tuple by calling either the Tuple constructor or the static Tuple.Create() method.

 // Instantiate using constructor 
 Tuple<int, string, int> t1 = new Tuple<int, string, int>(3, "Frank", 9);

 // Instantiate using create method 
 Tuple<int, int, int> t2 = Tuple.Create(3, 5, 9);

Tuple constructor and create() method can contain a maximum of 8 parameters. You have to take care of the 8th parameter because it replaces another tuple object.

Simple Use of Tuple

You can easily return more than one value from method without using out or ref parameters.

 public Tuple<int, int> SplitPoints(string point)
    string[] pointList = point.Split(',');

    int x = Convert.ToInt32(pointList[0]);
    int y = Convert.ToInt32(pointList[1]);
    return Tuple.Create<int, int>(x, y);

SplitPoints method split the points and returns x and y points in tuple.

 Tuple<int,int> points = SplitPoints("12,14");           
 string msg = string.Format("X: {0}, Y: {1}", points.Item1, points.Item2);

You can get the returned values from exposed properties Item1, Item2, etc. by Tuple object. Item properties of Tuple object are readonly. You can not change the value of the property.

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