gethashcode

I have an enum public enum INFLOW_SEARCH_ON { ON_ENTITY_HANDLE = 0, ON_LABEL = 1, ON_NODE_HANDLE = 2 } // enum INFLOW_SEARCH_ON I have to use this enum for searching in a grid column. To get the column index I am using MyEnumVariable.GetHashCode() Which works ok, or should I use (short)MyEnumVariable I am a bit confused over using GetHashCode() . Is there any problem using that? Using GetHashCode() is incorrect. You should cast to int . Using it the way you do is asking for raptors(or Raymond) to come and eat you. That GetHashCode() happens to return the integer value of the enum is an

Should we override both Equals and GetHashCode properties when implementing a custom class instances comparison? In the following code I have a collection of classes. The class A is compared by the ID , the class B - by Code . using System; using System.Collections.Generic; using System.Diagnostics; using System.Linq; namespace ConsoleApplication2 { class Program { static void Main(string[] args) { List<I> bars = new List<I>(); bars.Add(new A() { Id = 1, Code = "one A" }); bars.Add(new B() { Id = 1, Code = "one B" }); bars.Add(new A() { Id = 1, Code = "one A+" }); bars.Add(new B() { Id = 1,

I have an object for which I want to generate a unique hash (override GetHashCode()) but I want to avoid overflows or something unpredictable. The code should be the result of combining the hash codes of a small collection of strings. The hash codes will be part of generating a cache key, so ideally they should be unique however the number of possible values that are being hashed is small so I THINK probability is in my favour here. Would something like this be sufficient AND is there a better way of doing this? int hash = 0; foreach(string item in collection){ hash += (item.GetHashCode() /

So I'm trying to figure out how to correctly override GetHashCode() in VB for a large number of custom objects. A bit of searching leads me to this wonderful answer . Except there's one problem: VB lacks both the checked and unchecked keyword in .NET 4.0. As far as I can tell, anyways. So using Jon Skeet's implementation, I tried creating such an override on a rather simple class that has three main members: Name As String , Value As Int32 , and [Type] As System.Type . Thus I come up with: Public Overrides Function GetHashCode() As Int32 Dim hash As Int32 = 17 hash = hash * 23 + _Name

In search of a fast composite key for Dictionary I came upon anomaly I cannot understand nor justify. In limited testing Dictionary<KeyValuePair<UInt32, UInt32>, string> is significantly slower (200:1) than Dictionary<KeyValuePair<UInt16, UInt16>, string> Test on two loops from 0 to 1000 Populate and then ContainsKey Poplulate ContainsKey UInt32 92085 86578 UInt16 2201 431 The problem is that new KeyValuePair<UInt32, UInt32>(i, j).GetHashCode(); yields MANY duplicates. In looping i and j 1024 only 1024 unique hash values are created. Based on avalanche comment from CasperOne tried i*31 and j

Many of my questions here on SO concerns IEquatable implementation. I found it being extremely difficult to implement correctly, because there are many hidden bugs in the naïve implementation, and the articles I found about it are quite incomplete. I want to find or write a definitive reference which must include: How to implement IEquatable correctly How to override Equals correctly How to override GetHashCode correctly How to implement the ToString method correctly How to implement the operator == correctly How to implement the operator != correctly Such a complete reference already exists?