TOPIC 11.3.1
Differences in Appending Files
The Macintosh CodeWarrior compiler does not support the use of ios::app alone as a valid stream operation. Consult CodeWarrior's documentation if you are using the CodeWarrior compiler.
When opening a file for appending, use both the ios::out and ios::app operation modes. For example, instead of
outfile.open("NAME_AGE.DAT", ios::app);
use
outfile.open("NAME_AGE.DAT", ios::out | ios::app);