Editing Indentation style (section)

=== BSD KNF ===

The [[Berkeley Software Distribution]] (BSD) operating systems uses a style that is sometimes termed [[kernel normal form]] (KNF). Although mostly intended for kernel code, it is also widely used in [[userland (computing)|userland]] code. It is essentially a thoroughly documented variant of K&R style as used in the Bell Labs version 6 & 7 [[Unix]] source code.<ref name="C Style and Coding Standards for SunOS">{{cite news |last1=Shannon |first1=Bill |title=C Style and Coding Standards for SunOS |url=https://www.cis.upenn.edu/~lee/06cse480/data/cstyle.ms.pdf |access-date=15 June 2019 |version=1.8 |publisher=Sun Microsystems, Inc. |date=19 August 1996}}</ref>

The SunOS kernel and userland uses a similar indentation style.<ref name="C Style and Coding Standards for SunOS" /> Like KNF, this also was based on AT&T style documents and is sometimes termed Bill Joy Normal Form.<ref name="DTraceToolkit Style Guide">{{cite web |last1=Gregg |first1=Brendan |title=DTraceToolkit Style Guide |url=http://www.brendangregg.com/DTraceToolkit/style.html |access-date=6 February 2015}}</ref> The SunOS guideline was published in 1996; ANSI C is discussed briefly. The correctness of the indentation of a list of source files can be verified by the ''cstyle'' program written by Bill Shannon.<ref name="C Style and Coding Standards for SunOS" /><ref name="DTraceToolkit Style Guide" /><ref name="illumos-gate cstyle">{{cite web |url=https://github.com/illumos/illumos-gate/blob/master/usr/src/tools/scripts/cstyle.pl |title=cstyle.pl |last1=Shannon |first1=Bill |date=9 September 1998 |website=illumos-gate |publisher=Sun Microsystems, Inc. |access-date=6 February 2015 |version=1.58}}</ref>

In this style, the hard tabulator (ts in [[Vi (text editor)|vi]]) is kept at eight columns, while a soft tabulator is often defined as a helper also (sw in vi), and set at four. The hard tabulators are used to indent code blocks, while a soft tabulator (four spaces) of additional indentation is used for all continuing lines that must be split over multiple lines.

Moreover, function calls do not use a space before the parenthesis, although C-language native statements such as <code>if</code>, <code>while</code>, <code>do</code>, <code>switch</code> and <code>return</code> do (in the case where <code>return</code> is used with parens). Functions that declare no local variables in their top-level block should also leave an empty line after their opening block brace.

Examples:

<syntaxhighlight lang=c>
while (x == y) {
        something();
        something_else();
}
final_thing();
</syntaxhighlight>

<syntaxhighlight lang=c>
if (data != NULL && res > 0) {
        if (JS_DefineProperty(cx, o, "data",
            STRING_TO_JSVAL(JS_NewStringCopyN(cx, data, res)),
            NULL, NULL, JSPROP_ENUMERATE) != 0) {
                QUEUE_EXCEPTION("Internal error!");
                goto err;
        }
        PQfreemem(data);
} else {
        if (JS_DefineProperty(cx, o, "data", OBJECT_TO_JSVAL(NULL),
            NULL, NULL, JSPROP_ENUMERATE) != 0) {
                QUEUE_EXCEPTION("Internal error!");
                goto err;
        }
}
</syntaxhighlight>

<syntaxhighlight lang=c>
static JSBool
pgresult_constructor(JSContext *cx, JSObject *obj, uintN argc,
    jsval *argv, jsval *rval)
{

        QUEUE_EXCEPTION("PGresult class not user-instantiable");

        return (JS_FALSE);
}
</syntaxhighlight>