There are many answers already on the subject, but I can't find any that looks like what I'm looking for.
I would need to generate a unique negative ID (int) from a given string. Would be happy if there was the decoding as well, but not mandatory.
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6Unique in what context? Universally, per network, per computer, per session, per user, per process, or what?Matthew Watson– Matthew Watson2013-04-15 10:10:41 +00:00Commented Apr 15, 2013 at 10:10
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3 Answers
You could try myString.GetHashCode() it's not guaranteed to be unique, but will definetely return the same key for the same string.
2 Comments
Matthew Watson
And if it isn't already negative, he'd need to negate it. That's going to double the number of collisions of course.
jasdefer
"The hash code itself is not guaranteed to be stable. Hash codes for identical strings can differ across versions of the .NET Framework and across platforms (such as 32-bit and 64-bit) for a single version of the .NET Framework. In some cases, they can even differ by application domain." msdn.microsoft.com/en-us/library/…
Obviously, there is no such conversion. int size is limited by 32 bits, while string size is pretty much unlimited. You will get collisions unless you apply some restrictions to your strings.
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goul
Good remark. I am using the answer proposed below but will pay attention to my string length. thanks
It is impossible to generate a unique int for an arbitrary length string.
int has 32 bits of data, a string of 100 characters (assuming C#) will have 1600 bits of data, so you will have at least 1600/32 collisions.
[being funny]
you could :
string a = "dgfadg";
var bytes = System.Text.Encoding.Unicode.GetBytes(a);
BigInteger integer= new BigInteger(bytes);
[/being funny]
