Practical Programming, 2nd Edition

Multiline Records

Not every data record will fit onto a single line. Here is a file in simplified Protein Data Bank (PDB) format that describes the arrangements of atoms in ammonia:

COMPND      AMMONIA
ATOM      1  N  0.257  -0.363   0.000
ATOM      2  H  0.257   0.727   0.000
ATOM      3  H  0.771  -0.727   0.890
ATOM      4  H  0.771  -0.727  -0.890
END

The first line is the name of the molecule. All subsequent lines down to the one containing END specify the ID, type, and XYZ coordinates of one of the atoms in the molecule.

Reading this file is straightforward using the techniques we have built up in this chapter. But what if the file contained two or more molecules, like this:

COMPND      AMMONIA
ATOM      1  N  0.257  -0.363   0.000
ATOM      2  H  0.257   0.727   0.000
ATOM 3 H 0.771 -0.727 ...