A Complete Program
/* $NetBSD: echo.c,v 1.7 1997/07/20 06:07:03 thorpej Exp $ */
/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT(
"@(#) Copyright (c) 1989, 1993\n\
The Regents of the University of California. All rights reserved.\n");
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)echo.c 8.1 (Berkeley) 5/31/93";
#else
__RCSID("$NetBSD: echo.c,v 1.7 1997/07/20 06:07:03 thorpej Exp $");
#endif
#endif /* not lint */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int __Pmain ((int, char *[]));
main(argc, argv)
int argc;
char *argv[];
{
int nflag;
/* This utility may NOT do getopt(3) option parsing. */
if (*++argv && !strcmp(*argv, "-n")) {
++argv;
nflag = 1;
}
else
nflag = 0;
while (*argv) {
(void)printf("%s", *argv);
if (*++argv)
putchar(' ');
}
if (!nflag)
putchar('\n');
exit(0);
}
Important issues:
- Headers
- Old-style declarations vs.
int main(int argc, char *argv[]);
- getopt
- strcmp return value. Common idiom:
#define STREQ(a, b) (*(a) == *(b) && strcmp((a), (b)) == 0)
- Java argv processing:
if (isConfig) {
configFile = args[i];
isConfig = false;
} else if (args[i].equals("-config")) {
isConfig = true;
} else if (args[i].equals("-debug")) {
debug = true;
} else if (args[i].equals("-nonaming")) {
- Variable initialization (nflag)
- printf and format specifications
- printf and putchar return value
if (ferror(stdout))
err(1, "stdout");