[TUHS] // comment in C++

Doug McIlroy doug at cs.dartmouth.edu
Fri Feb 10 07:14:30 AEST 2017


With no offense intended, I can't help noting the irony of the
following paragraph appearing in a message in the company of
others that address Unix "bloat".

>'\cX'    A mechanism that allows usage of the non-printable
>          (ASCII and compatible) control codes 0 to 31: to cre-
>          ate the printable representation of a control code the
>          numeric value 64 is added, and the resulting ASCII
>          character set code point is then printed, e.g., BEL is
>          '7 + 64 = 71 = G'.  Whereas historically circumflex
>          notation has often been used for visualization pur-
>          poses of control codes, e.g., '^G', the reverse
>          solidus notation has been standardized: '\cG'.  Some
>          control codes also have standardized (ISO 10646, ISO
>          C) alias representations, as shown above (e.g., '\a',
>          '\n', '\t'): whenever such an alias exists S-nail will
>          use it for display purposes.  The control code NUL
>          ('\c@') ends argument processing without producing
>          further output.

Except for the ISO citations, this paragraph says the same
thing more succinctly.

'\cX'    represents a nonprintable character Y in terms of the
          printable character X whose binary code is obtained
          by adding 0x40 (decimal 64) to that for Y. (In some
          historical contexts, '^' plays the role of '\c'.)
          Alternative standard representations for certain
          nonprinting characters, e.g. '\a', '\n', '\t' above,
          are preferred by S-nail. '\c@' (NUL) serves as a
          string terminator regardless of following characters.

And this version, 1/3 the length of the original, tells all
one really needs to know.

'\cX'    represents a nonprintable character Y in terms of the
          printable character X whose binary code is obtained
          by adding 0x40 (decimal 64) to that for Y. '\c@'
          (NUL) serves as a string terminator regardless of
          following characters.

Doug]


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