ptg10805159Chapter 5 Exercises 175
Section 7.8). As with thesfiopackage, ASI attempts to minimize the amount of data
copying by using pointers.
Several implementations of the standardI/O library areavailable in C libraries that
weredesigned for systems with small memory footprints, such as embedded systems.
These implementations emphasize modest memory requirements over portability,
speed, or functionality.Two such implementations arethe uClibc C library (see
http://www.uclibc.org for moreinformation) and the Newlib C library
(http://sources.redhat.com/newlib).5.16 Summary
The standardI/O library is used by most UNIX applications. In this chapter, we looked
at many of the functions provided by this library, as well as at some implementation
details and efficiency considerations. Be aware of the buffering that takes place with
this library, as this is the area that generates the most problems and confusion.Exercises
5.1 Implementsetbufusingsetvbuf.
5.2 Type in the program that copies a file using line-at-a-time I/O (fgetsandfputs)from
Figure5.5, but use aMAXLINEof 4. What happens if you copy lines that exceed this length?
Explain what is happening.
5.3 What does a return value of 0 fromprintfmean?
5.4 The following code works correctly on some machines, but not on others. What could be
the problem?
#include <stdio.h>
int
main(void)
{
char c;
while ((c = getchar()) != EOF)
putchar(c);
}5.5 How would you use thefsyncfunction (Section 3.13) with a standardI/O stream?
5.6 In the programs in Figures 1.7 and 1.10, the prompt that is printed does not contain a
newline, and we don’t callfflush.What causes the prompt to be output?
5.7 BSD-based systems provide a function calledfunopenthat allows us to intercept read,
write, seek, and close calls on a stream. Use this function to implementfmemopenfor
FreeBSD and Mac OS X.