[c#] get name of a variable or parameter

Alternatively,

1) Without touching System.Reflection namespace,

GETNAME(new { myInput });

public static string GETNAME<T>(T myInput) where T : class
{
    if (myInput == null)
        return string.Empty;

    return myInput.ToString().TrimStart('{').TrimEnd('}').Split('=')[0].Trim();
}

2) The below one can be faster though (from my tests)

GETNAME(new { variable });
public static string GETNAME<T>(T myInput) where T : class
{
    if (myInput == null)
        return string.Empty;

    return typeof(T).GetProperties()[0].Name;
}

You can also extend this for properties of objects (may be with extension methods):

new { myClass.MyProperty1 }.GETNAME();

You can cache property values to improve performance further as property names don't change during runtime.

The Expression approach is going to be slower for my taste. To get parameter name and value together in one go see this answer of mine