dsr-pdb is a simple C++ PDB reader along with a couple of programs which use it
to manipulate pdb files (applying a rigid transform or splitting/merging). The
are aimed at people interested in proteins from a geometric viewpoint as they
allow easy access to the geometry and bond structure in addition of the
biological information. The reader has two modes for reading/writing a pdb file.
The simplest one, through the Protein class just reads and writes a single
protein from/to a pdb file (which must have only one chain, but can have
multiple models). The second, through the PDB class can handle pdb files with
multiple models and herogens (although these are just passed through and not
currently interpreted).

WWW: https://graphics.stanford.edu/~drussel/pdb/