Generating a Unique ID in c++

Question

What is the best way to generate a Unique ID from two (or more) short ints in C++? I am trying to uniquely identify vertices in a graph. The vertices contain two to four short ints as data, and ideally the ID would be some kind of a hash of them. Prefer portability and uniqueness over speed or ease.

There are a lot of great answers here, I will be trying them all tonight to see what fits my problem the best. A few more words on what I'm doing.

The graph is a collection of samples from an audio file. I use the graph as a Markov Chain to generate a new audio file from the old file. Since each vertex stores a few samples and points to another sample, and the samples are all short ints, it seemed natural to generate an ID from the data. Combining them into a long long sounds good, but maybe something as simple as just a 0 1 2 3 generateID is all I need. not sure how much space is necessary to guarantee uniqueness, if each vertex stores 2 16 bit samples, there are 2^32 possible combinations correct? and so if each vertex stores 4 samples, there are 2^64 possible combinations?

Library and platform specific solutions not really relevant to this question. I don't want anyone else who might compile my program to have to download additional libraries or change the code to suit their OS.

Answer 1

Sometimes the simplest things works best.

Can you just add an id field to the Vertex object and assign it a number in order of construction?

static int sNextId = 0;
int getNextId() { return ++sNextId; }