Before you march off and use one of the examples someone's already given you should be aware that there is, in general, no unique mapping between a string and a sequence of bytes. How the string is mapped to binary (and vice versa) is determined by the encoding that you use. Joel Spolsky wrote an awesome article on this subject.
When decoding binary to get a string, you need to use the same encoding as was used to produce the binary in the first place, otherwise you'll run into problems.
