.Contains() on a list of custom class objects

Question

I'm trying to use the .Contains() function on a list of custom objects

This is the list:

List<CartProduct> CartProducts = new List<CartProduct>(); 

And the CartProduct:

public class CartProduct {     public Int32 ID;     public String Name;     public Int32 Number;     public Decimal CurrentPrice;     /// <summary>     ///      /// </summary>     /// <param name="ID">The ID of the product</param>     /// <param name="Name">The name of the product</param>     /// <param name="Number">The total number of that product</param>     /// <param name="CurrentPrice">The currentprice for the product (1 piece)</param>     public CartProduct(Int32 ID, String Name, Int32 Number, Decimal CurrentPrice)     {         this.ID = ID;         this.Name = Name;         this.Number = Number;         this.CurrentPrice = CurrentPrice;     }     public String ToString()     {         return Name;     } } 

So i try to find a similar cartproduct within the list:

if (CartProducts.Contains(p)) 

But it ignores similar cartproducts and i don't seem to know what it checks on - the ID? or it all?

Thanks in advance! :)

Answer 1

If you are using .NET 3.5 or newer you can use LINQ extension methods to achieve a "contains" check with the Any extension method:

if(CartProducts.Any(prod => prod.ID == p.ID)) 

This will check for the existence of a product within CartProducts which has an ID matching the ID of p. You can put any boolean expression after the => to perform the check on.

This also has the benefit of working for LINQ-to-SQL queries as well as in-memory queries, where Contains doesn't.