feat: GUID

CarManagerV3/CarDetailsForm.cs

@@ -21,7 +21,7 @@ namespace CarManagerV3
             nudPrice.Value = car.Price;
             tbxAge.Text = car.AgeString;
             pbxCarImage.Image = ImageManager.GetImage(car);
-            if (car.Id == 0)
+            if (car.Id == "0")
             {
                 lblID.Text = "New Car";
             }
@@ -125,7 +125,7 @@ namespace CarManagerV3
             msgbox.Show();
             await Task.Run(() =>
             {
-                if(car.Id == 0) {
+                if(car.Id == "0") {
                     car = StateManager.CreateCar(car.Make, car.Model, car.Year, car.Color, car.Mileage, car.Price);
                 }
                 else { 
@@ -145,7 +145,7 @@ namespace CarManagerV3
 
         private void btnDelete_Click(object sender, EventArgs e)
         {
-            if(car.Id == 0)
+            if(car.Id == "0")
             {
                 //just close form if car is not saved yet
                 this.Close();