How set value in tuple c#

In addition to solution 1 by ProgramFox[^], i'd suggest to read this very interesting article: C# 4 - Tuples[^]. MSDN migh be helpful too: Tuple Class[^]

Note: Tuples are very useful, but you have to work on specific data type, for example custom class. You can "transform" tuple to custom data type (class) via using Linq query. See: Using your own defined type in a LINQ query expression[^]

Let's say, you have custom class as follow:

public class Whatever
{
    private string sProp = string.Empty;
    private int iVal = 0;

    public Whatever()
    {
    }

    public Whatever(string _Prop, int _Val)
    {
        sProp = _Prop;
        iVal = _Val;
    }

    public string Prop
    {
        get{ return sProp; }
        set{ sProp = value; }
    }
    public int Val
    {
        get{ return iVal; }
        set{ iVal = value; }
    }
}

Now, you want to create list of your data... and change first element:

//list of tuples
List<Tuple<string, int>> MyTuple = new List<Tuple<string, int>>()
        {
            new Tuple<string, int>("A", 1),
            new Tuple<string, int>("A", 10),
            new Tuple<string, int>("A", 100)
        };

//transform to custom class collection
List<Whatever> ClassCollectionFromTupple = (from mt in MyTuple
    select new Whatever
        {
            Prop = mt.Item1,
            Val = mt.Item2
        }).ToList();

//get specific element
Whatever wr = ClassCollectionFromTupple[0];
//change value
wr.Val = 3;

Try! And Good Luck!

Possibly a bit overkill for most situations, but you could consider wrapping the (tuple) items with a container type - the Tuple<> indirectly referencing each of the items (via the container type/instance), whereby you can change the container's (item) value (- just not the container itself - that is immutably referenced by the parent Tuple<> / what it directly sees as been Item1 & Item2).