Dictionary.ContainsKey return False, but a want True

Question

namespace Dic
{
public class Key
{
    string name;
    public Key(string n) { name = n; }
}

class Program
{
    static string Test()
    {
        Key a = new Key(         


        

Answer 1

If you do not have the ability to override equality operators/Equals/GetHashCode as others have mentioned (as in, you do not control the source code of the object), you can provide an IEqualityComparer implementation in the constructor of the dictionary to perform your equality checks.

class KeyComparer : IEqualityComparer
{
    public bool Equals(Key x, Key y)
    {
        return x.Name == y.Name;
    }

    public int GetHashCode(Key obj)
    {
        return obj.Name.GetHashCode();
    }
}

As it stands, your Key is a reference object, so equality is only determined on reference unless you tell the world (or the dictionary) otherwise.