Question Store child class in parent list and then find the specific child in the list

Hello,

I have 2 child classes which derived from parent class:

Parent class:
Animal

Child Class 1 :
Dog

Child Class 2:
Bird


I'm storing instance of Dog and Cat inside List<Animal> animals = new List<Animal>();

And then want to loop inside animal list to find all instances of dog or cat.

But actually i'm getting error - I know why it happend's, it because when I search for dogs is also loop in cat elements
but dog is not cat , so I'm getting cast problem.

I'm very sure that there is smarter way to do it.

I attached the my code:

Code (CSharp):

1. public class programClass
2.  
3. {
4.     public Animal insTClass;
5.     public List<Animal> components;
6.  
7.  
8.     public void CreateNewList()
9.     {
10.         components = new List<Animal>();
11.      
12.  
13.     }
14.     public void instanceMethod<T>() where T : Animal, new()  // Im storing Cat and dogs from another script(storeManager).
15.     {
16.         insTClass = new T();
17.         components.Add(insTClass);
18.         insTClass.parentID = insTClass.ToString();
19.     }
20.  
21.     public T searchInList<T>() where T : Animal  // search for cat inside animal
22.     {
23.         foreach (T instclass in components)   // Here im getting the error.
24.         {
25.             if (instclass.parentID != instclass.ToString())
26.             {
27.                 continue;
28.             }
29.             return instclass;
30.         }
31.         return null;
32.     }

 

You shouldn't rely on

ToString

to do type testing. Use the

is

and

as

operators instead.

But in your case, the cast error happens before that.

foreach

will always iterate over all elements, so you need to use

Animal

there and then check the type later. You can use

VAR is TYPE NEW_NAME

to check the type and assign it to a variable if the type matches in a single line.

Code (CSharp):

1. public T searchInList<T>() where T : Animal  // search for cat inside animal
2. {
3.     foreach (Animal comp in components)   // Here im getting the error.
4.     {
5.         if (comp is T instclass)
6.         {
7.             return instclass;
8.         }
9.     }
10.     return null;
11. }

 

Thanks,
Great . work smooth..