I'm testing the VB function below that I got from a Google search. I plan to use it to generate hash codes for quick string comparison. However, there are occasions in which two different strings have the same hash code. For example, these strings "122Gen 1 heap size (.NET CLR Memory w3wp):mccsmtpteweb025.20833333333333E-02" "122Gen 2...
Like many of you, I use ReSharper to speed up the development process. When you use it to override the equality members of a class, the code-gen it produces for GetHashCode() looks like: public override int GetHashCode() { unchecked { int result = (Key != null ? Key.GetHashCode() : 0); res...
So I'm reading up about hash tables, hash functions etc. I was intrigued to read on wikipedia about how "dynamic perfect hashing" involves using a second hash table as the data structure to store multiple values within a particular bucket. Where I get lost however, is when it comes to how a universal hash function is selected to perfor...
WinForms / C# My application allows the user to specify 1) additional information for 2) a given file, both of which are uploaded to the server. There are two isolated uploads: first the file, and (maybe much) later the metadata. Please assume the file to be always unchanged and available (to the code). When the metadata is uploaded,...
I have a system that requires a unique 6-digit code to represent an object, and I'm trying to think of a good algorithm for generating them. Here are the pre-reqs: I'm using a base-20 system (no caps, numbers, vowels, or l to prevent confusion and naughty words) The base-20 allows 64 million combinations I'll be inserting potentially...
This is more of a cryptography theory question, but is it possible that the result of a hash algorithm will ever be the same value as the source? For example, say I have a string: baf34551fecb48acc3da868eb85e1b6dac9de356 If I get the SHA1 hash on it, the result is: 4d2f72adbafddfe49a726990a1bcb8d34d3da162 In theory, is there ever a...
Hi, I have a pretty complex object and I need to get uniqueness of these objects. One solution can be done by overriding GetHashCode(). I have implemented a code noted below: public override int GetHashCode() { return this._complexObject1.GetHashCode() ^ this._complexObject2.GetHashCode() ^ this._complexObject...
If I'm hashing size-constrained similar data (social security numbers, for example) using a hash algorithm with a larger byte size than the data (sha-256, for example), will the hash guarantee the same level of uniqueness as the original data? ...
I'm hashing a large number of files, and to avoid hash collisions, I'm also storing a file's original size - that way, even if there's a hash collision, it's extremely unlikely that the file sizes will also be identical. Is this sound (a hash collision is equally likely to be of any size), or do I need another piece of information (if a ...