Property changed event C#

    public event PropertyChangedEventHandler PropertyChanged;

    protected void SetField<T>(ref T field, T value, [CallerMemberName] string propertyName = null)
    {
        if (EqualityComparer<T>.Default.Equals(field, value)) return;
        field = value;
        OnPropertyChanged(propertyName);
    }

    protected virtual void OnPropertyChanged([CallerMemberName]string propertyName = null) =>
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));

Subscribe to property change

ChattyClass tmp = new ChattyClass();
tmp.PropertyChanged += (sender, e) =>
    {
        Console.WriteLine(string.Format("Property {0} has been updated", e.PropertyName));
    };