How to make a dictionary library and read from it?

I have many bits, say for example k=randi([0,1],1,10000), I want to segment it into 3 bits, and turn these bits into codewords, C=c1,c2,...,c8.

I think I have to save them in a dictionary, or a cell. And then ask whether these codeword matches each three bits or not?

But I dont konw how, because I am new in matlab.

Can you help?

thanks