The Ten Commandments for C Programmers

Henry Spencer

1. Thou shalt run Lint frequently and study its pronounce-
   ments with care, for verily its perception and judge-
   ment oft exceed thine.
   
2. Thou shalt not follow the NULL pointer, for chaos and
   madness await thee at its end.
   
3. Thou shalt cast all function arguments to the expected
   type if they are not of that type already, even when
   thou art convinced that this is unnecessary, lest they
   take cruel vengeance upon thee when thou least expect
   it.
   
4. If thy header files fail to declare the return types of
   thy library functions, thou shalt declare them thyself
   with the most meticulous care, lest grievous harm
   befall thy program.
   
5. Thou shalt check the array bounds of all strings
   (indeed, all arrays), for surely where thou typest
   ``foo'' someone someday shall type ``supercalifragilis-
   ticexpialidocious''.
   
6. If a function be advertised to return an error code in
   the event of difficulties, thou shalt check for that
   code, yea, even though the checks triple the size of
   thy code and produce aches in thy typing fingers, for
   if thou thinkest ``it cannot happen to me'', the gods
   shall surely punish thee for thy arrogance.
   
7. Thou shalt study thy libraries and strive not to re-
   invent them without cause, that thy code may be short
   and readable and thy days pleasant and productive.
   
8. Thou shalt make thy program's purpose and structure
   clear to thy fellow man by using the One True Brace
   Style, even if thou likest it not, for thy creativity
   is better used in solving problems than in creating
   beautiful new impediments to understanding.
   
9. Thy external identifiers shall be unique in the first
   six characters, though this harsh discipline be irksome
   and the years of its necessity stretch before thee
   seemingly without end, lest thou tear thy hair out and
   go mad on that fateful day when thou desirest to make
   thy program run on an old system.
   
10. Thou shalt foreswear, renounce, and abjure the vile
    heresy which claimeth that ``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.