a list of rules that every c programmer should follow

8/13/2019 A List of Rules That Every C Programmer Should Follow

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)ever call a function without chec-ing its error return. *f the error is

impossible, at least call assert!, as in this e0ample3 if "close"fd# ??

assert"485#6

Chec- null pointers against ):44, never against ' or anything else. (o not

cast ):443 if "flurb"0, y# ?? "struct 9cd =#):44# = bad = D

;hen you have an initialiEation, a test, and an incrementation, use a for! loop

instead of a while! loop. This ma-es the loop control more e0plicit and

reduces the possibility of forgetting to increment.

;hen calling a function that returns a useful value or an error return, use this

assign and chec-! paradigm3

if ""p ? fcn"0, y## ?? ):44#

D handle error D

;hile ordinarily * would recommend against doing assignment in the middle

of an e0pression, this is an e0ception. *t occurs so often that its immediately

recogniEable to the e0perienced reader, re


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length e0clusive of the ):4 byte, and then add one for dimensioning. The

alternative is, of course, also OK.

5very switch! statement should have a default! case, to reduce debugging.

*f it cant ever occur, use assert!3

switch "0# LD

default3

assert"485#6

*f your compiler supports function prototypes, always use them, both for

library functions and for your own. They are the greatest contribution to C

programming since the curly brace. *ve found this paradigm useful for static

functions, as it ma-es modifications easier3

static 2OO45) fcn"int, float#6static 2OO45) fcn"count, val#

int count6

float val6

L

D

)ote that come compilers are set up to ignore library prototypes by default. or

e0ample, with Microsoft C you have to define the symbol 4*)TN98!.

ind out what compiler options generate the most warnings and the strictest

error chec-ing, and turn them on. Ma-e sure all of your files compile with no

warnings at all, or else youll miss a new warning because its mi0ed in with

the old ones. (oing this will often mean that youll use lots of casts. 2ut

dont +ust blindly put in a cast to ma-e a warning go away, or you might

overloo- an actual bug.

How you lay out your programs is a matter of personal preference. 2ut at

least be consistent, or you ris- telling the reader that you dont -now what

youre doing. 5ither put a statement on the same line as the if!, or on the

ne0t line, but dont do it sometimes one way and sometimes the other. /utblan-s between a function name and the left parenthesis, or dont, but always

do it the same way. 8ince all bugs are introduced during te0t editing, thats

when you need a consistent style. 8o, dont use a C beautifier, unless its to fi0

up a program someone else gave you.

Call assert! as often as you have the energy to. (ont define )(52:! to

remove assertions when your program is ready for delivery, because thats

when undiscovered bugs have their worst conse


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Marc P. 9och-ind

ebruary J, &QJ

Compu8erve J%JR%,&ISS

Copyright &QJ dvanced /rogramming *nstitute, 4td. May be freely reproduced and

distributed, but only in its entirety, with no editing whatsoever, e0cept thatmisspellings may have the mar-ing sicU! inserted after them, li-e thas sicU. The

authors name and this Copyright notice must be included.

a list of rules that every c programmer should follow

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