Question

I have this class Variables

public class Variables
{

    public enum DataType
    {
        INT, CHAR, BOOL, FLOAT
    }

    public string Name { get; set; }
    public DataType Type { get; set; }
    public object Value { get; set; }

    public Variables(string name, DataType type, object value)
    {
        Name = name;
        Type = type;
        Value = value;
    }

}

It is also assumed that Name is unique. And inside another class I have a list of variables, List<Variables>

public void Main()
{
    List<Variables> varList = new List<Variables>();
    varList.Add(new Variables("x",DataType.BOOL, true));
    varList.Add(new Variables("y",DataType.BOOL, false));
    varList.Add(new Variables("z",DataType.BOOL, true));
    varList.Add(new Variables("a",DataType.INT, 1));
    varList.Add(new Variables("b",DataType.INT, 10));

    // I need this to convert into LiNQ.
    foreach (Variables _x in varList)
    {
        if (_x.Name == "z")
        {
            _x.Value = false;
        }
    }
}

How can I convert foreach into LiNQ? I tried .Where, .Select but they return IEnumerable. Is there a LinQ method that returns only a single value that matches to a given condition? eg,

Variables _var = varList.MethodName(LambDa Expression).....

Answer 1

Well you can use Single:

varList.Single(x => x.Name == "z").Value = false;

That will fail if there’s anything other than exactly one match though.

Alternatives are SingleOrDefault, FirstOrDefault, First, LastOrDefault and Last. For example, if you expect “0 or 1” results:

var match = varList.SingleOrDefault(x => x.Name == "z");
if (match != null)
{
    match.Value = false;
}