By Henry Spencer. Translation into XHTML by J. Blustein.
The original version was posted to Usenet's comp.lang.c newsgroup (Message-ID: <8771@utzoo.UUCP>) in the year 1987. An annotated version was posted to the same newsgroup in the year 1990 (Message-ID: <1990Nov4.email@example.com>). Links to some other versions of this list are at the end.
I wish to completely dissociate myself from the metaphorical use of
Gestapo which I find deeply offensive. I include
it here only to provide an accurate translation. I did however
correct four typos in
the original and add some links and annotations of my own. The
links I added are indicated by footnote symbols (*
This is still wise counsel, although many modern compilers search out many of the same sins, and there are often problems with lint being aged and infirm, or unavailable in strange lands. There are other tools, such as Saber C, useful to similar ends.
Frequently means thou shouldst draw thy daily guidance
from it, rather than hoping thy code will achieve lint's blessing by a sudden act of repentance at the
last minute. De-linting a program which has
never been linted before is often a cleaning of
the stables such as thou wouldst not wish on thy worst enemies.
Some observe, also, that careful heed to the words of lint can be quite helpful in debugging.
Study doth not mean mindless zeal to eradicate every
byte of lint output — if for no other
reason, because thou just canst not shut it up about some things
— but that thou should know the cause of its unhappiness and
understand what worrisome sign it tries to speak of.
NULLpointer, for chaos and madness await thee at its end.
Clearly the holy scriptures were mis-transcribed here, as the words
should have been
null pointer, to minimize confusion
between the concept of null pointers and the macro
which more anon). Otherwise, the meaning is plain. A null
pointer points to regions filled with dragons, demons, core dumps, and
numberless other foul creatures, all of which delight in frolicking in thy program if thou disturb their sleep. A
null pointer doth not point to a
0 of any type,
despite some blasphemous old code which impiously assumes this.
A programmer should understand the type structure of his language, lest
great misfortune befall him. Contrary to the heresies espoused by
some of the dwellers on the Western Shore,
the same type. The moment of their equivalence in size and
representation is short, and the agony that awaits believers in their
interchangeability shall last forever and ever once 64-bit machines
Also, contrary to the beliefs common among the more backward
inhabitants of the Polluted Eastern Marshes,
does not have a pointer type, and
must be cast to the correct type whenever it is used as a function
(The words of the prophet Ansi, which
NULL to be defined as having the type
, are oft taken out of context and
misunderstood. The prophet was granting a special dispensation for
use in cases of great hardship in wild lands. Verily, a righteous
program must make its own way through the Thicket Of Types without
lazily relying on this rarely-available dispensation to solve all its
problems. In any event, the great deity Dmr who created C hath wisely endowed
it with many types of pointers, not just one, and thus it would still be
necessary to convert the prophet's
NULL to the desired
It may be thought that the radical new blessing of
prototypes might eliminate the need for caution
about argument types. Not so, brethren. Firstly, when
confronted with the twisted strangeness of variable numbers of
arguments, the problem returns
… and he who has not
kept his faith strong by repeated practice shall surely fall to this
subtle trap. Secondly, the wise men have observed that reliance on
prototypes doth open many doors to strange errors, and some indeed had
hoped that prototypes would be decreed for purposes of error checking
but would not cause implicit conversions. Lastly, reliance on
prototypes causeth great difficulty in the Real World today, when many
cling to the old ways and the old compilers out of desire or necessity,
and no man knoweth what machine his code may be asked to run on
The prophet Ansi, in her wisdom, hath added that thou shouldst also scourge thy Suppliers, and demand on pain of excommunication that they produce header files that declare their library functions. For truly, only they know the precise form of the incantation appropriate to invoking their magic in the optimal way.
The prophet hath also commented that it is unwise, and leads one into the pits of damnation and subtle bugs, to attempt to declare such functions thyself when thy header files do the job right.
foosomeone someday shall type
As demonstrated by the deeds of the Great Worm *, a consequence of this commandment is that robust production
software should never make use of
gets(), for it is truly a
tool of the Devil. Thy interfaces should always inform thy
servants of the bounds of thy arrays, and servants who spurn such advice
or quietly fail to follow it should be dispatched forthwith to the Land Of
Rm, where they can do no further harm to thee.
it cannot happen to me, the gods shall surely punish thee for thy arrogance.
All true believers doth wish for a better error-handling mechanism, for explicit checks of return codes are tiresome in the extreme and the temptation to omit them is great. But until the far-off day of deliverance cometh, one must walk the long and winding road with patience and care, for thy Vendor, thy Machine, and thy Software delight in surprises and think nothing of producing subtly meaningless results on the day before thy Thesis Oral or thy Big Pitch To The Client.
Occasionally, as with the
ferror() feature of
stdio, it is possible to defer error checking until the end
when a cumulative result can be tested, and this often produceth code
which is shorter and clearer. Also, even the most zealous believer
should exercise some judgement when dealing with functions whose failure
is totally uninteresting … but beware, for the cast to
void is a two-edged sword that sheddeth thine own blood
Numberless are the unwashed heathen who scorn their libraries on various
silly and spurious grounds, such as blind worship of the Little Tin God
(also known as
Efficiency). While it is true that some
features of the C libraries were ill-advised, by and large it is better
and cheaper to use the works of others than to persist in re-inventing
the square wheel. But thou should take the greatest of care to
understand what thy libraries promise, and what they do not, lest thou
rely on facilities that may vanish from under thy feet in future.
These words, alas, have caused some uncertainty among the novices and the converts, who knoweth not the ancient wisdoms. The One True Brace Style referred to is that demonstrated in the writings of the First Prophets, Kernighan and Ritchie. Often and again it is criticized by the ignorant as hard to use, when in truth it is merely somewhat difficult to learn, and thereafter is wonderfully clear and obvious, if perhaps a bit sensitive to mistakes†.
While thou might think that thine own ideas of brace style lead to clearer programs, thy successors will not thank thee for it, but rather shall revile thy works and curse thy name, and word of this might get to thy next employer. Many customs in this life persist because they ease friction and promote productivity as a result of universal agreement, and whether they are precisely the optimal choices is much less important. So it is with brace style.
As a lamentable side issue, there has been some unrest from the
fanatics of the Pronoun Gestapo over the use of the word
man in this Commandment, for they believe that great efforts and
loud shouting devoted to the ritual purification of the language will
somehow rebound to the benefit of the downtrodden
(whose real and grievous woes tendeth to get lost amidst all that
thunder and fury). When preaching the gospel to the narrow of mind
and short of temper, the word
creature may be
substituted as a suitable pseudoBiblical term free of the taint of
Though some hasty zealots cry
not so; the Millennium is come, and this saying is obsolete and
no longer need be supported, verily there be many, many ancient
systems in the world, and it is the decree of the dreaded god Murphy that thy next employment just might be on
one. While thou sleepest, he plotteth against thee. Awake
and take care.
It is, note carefully, not necessary that thy identifiers be limited to a length of six characters. The only requirement that the holy words place upon thee is uniqueness within the first six. This often is not so hard as the belittlers claimeth.
All the world's a VAX, and have no commerce with the benighted heathens who cling to this barbarous belief, that the days of thy program may be long even though the days of thy current machine be short.
This particular heresy bids fair to be replaced by
All the world's a Sun or
All the world's a '386 (this latter being a particularly
revolting invention of Satan), but the words apply to all such without
limitation. Beware, in particular, of the subtle and terrible
All the world's a 32-bit machine, which is almost true today but
shall cease to be so before thy resumé grows too much