If line 12 opens the file successfully, the program begins processing data. Lines 21–22 prompt the user to enter either the various fields for each record or the end-of-file indicator when data entry is complete. Figure 14.5 lists the keyboard combinations for entering end-of-file for various computer systems.
Line 29 extracts each set of data and determines whether end-of-file has been entered. When end-of-file is encountered or bad data is entered, operator void *
returns the null pointer (which converts to the bool
value false
) and the while
statement terminates. The user enters end-of-file to inform the program to process no additional data. The end-of-file indicator is set when the user enters the end-of-file key combination. The while
statement loops until the end-of-file indicator is set (or bad data is entered).
Line 31 writes a set of data to the file clients.txt
, using the stream insertion operator <<
and the outClientFile
object associated with the file at the beginning of the program. The data may be retrieved by a program designed to read the file (see Section 14.4). The file created in Fig. 14.3 is simply a text file, so it can be viewed by any text editor.