printf("this is going to be %s very long %s statement\n",
_______"a", "printf");
Comments may be single-line or multiline. A single-line comment should be at the end of the line of there is other text on the line, and should start in the same column as other nearby end-of-line comments. The comment should be at the same indentation level as the text it is referring to. Multiline comments should start with "/*" on a line by itself. Subsequent lines should have " *" lined-up with the "*" above. The end of the comment should be " */" on a line by itself, again with the "*" lined-up with the one above. Comments should start with a capital letter and end with a period.
Good:
/*
* Private variables.
*/
static int a /* Description of 'a'. */
static int b /* Description of 'b'. */
static char * c /* Description of 'c'. */
/* ARGSUSED */
/* FALLTHROUGH */
/* NOTREACHED */
/* VARARGS */
.h files that define modules should have a structure like the following:
/*
* Copyright (C) 1998 Internet Software Consortium.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
* SOFTWARE.
*/
#ifndef ISC_WHATEVER_H
#define ISC_WHATEVER_H 1
/*****
***** Module Info
*****/
/*
*
*
*
*
*
*
* MP:
*
*
* Reliability:
*
*
* Resources:
*
*
* Security:
*
*
* Standards:
*
*/
/***
*** Imports
***/
/* <#includes here> */
/***
*** Types
***/
/* */
/***
*** Functions
***/
#endif /* ISC_WHATEVER_H */
Operating-system-specific files should not be included by most modules.
Include UNIX "sys" .h files before ordinary C includes.
Bad:
if (i > 0) {
printf("yes\n"); i = 0; j = 0;
}
The return type of the function should be listed on a line by itself when specifying the implementation of the function. The opening curly brace should occur on the same line as the argument list, unless the argument list is more than one line long.
Good:
static inline void
f(int i) {
/* whatever */
}
int
g(int i, /* other args here */
int last_argument)
{
return (i * i);
}
Good:
static void
f(int i) {
if (i > 0) {
printf("yes\n");
i = 0;
} else
printf("no\n");
}
void f(int i)
{
if(i<0){i=0;printf("was negative\n");}
if (i > 0)
{
printf("yes\n");
i = 0;
}}
printf()?)All error conditions must be handled.
Mixing of error status and valid results within a single type should be avoided.
Good:
os_descriptor_t s;
os_result_t result;
result = os_socket_create(AF_INET, SOCK_STREAM, 0, &s);
if (result != OS_R_SUCCESS) {
/* Do something about the error. */
return;
}
int s;
/*
* Obviously using interfaces like socket() (below) is allowed
* since otherwise you couldn't call operating system routines; the
* point is not to write more interfaces like them.
*/
s = socket(AF_INET, SOCK_STREAM, 0);
if (s < 0) {
/* Do something about the error using errno. */
return;
}
Good:
/* Test if flag set. */
if ((flags & FOO) != 0) {
}
/* Test if flag clear. */
if ((flags & BAR) == 0) {
}
/* Test if both flags set. */
if ((flags & (FOO|BAR)) == (FOO|BAR)) {
}
/* Test if flag set. */
if (flags & FOO) {
}
/* Test if flag clear. */
if (! (flags & BAR)) {
}
Good:
char *c = NULL;
/* ... */
if (c == NULL) {
/* Do something. */
}
Good:
char *text;
/* text is initalized here. */
free(text);
text = NULL;
Good:
int i = 10;
/* ... */
if (i != 0) {
/* Do something. */
}
int i = 10;
/* ... */
if (i) {
/* Do something. */
}