To all:

Using double quotes in macros is easy to do using the # operator.  Now how
about single quotes.  Suppose you want preprocessor output to look like
this:

        char a = '\012';

given source of:

        #define SPECIAL_CHAR \012
        #define M(chr)  /* unknown macro definition here */

        char a = M(SPECIAL_CHAR);

How would you define the macro M to do the job?

Please try your solution before responding.

/cc

         #define SPECIAL_CHAR 012    /* Octal integer constant */

         char a = SPECIAL_CHAR;

--
-----------------------------------------


-----------------------------------------

        #define SPECIAL_CHAR    012  /* or char constant? */

        char a = 012;           /* or a = '\012' */
        const char *b = "some text with a char \012";

from source similar to:

        #define SPECIAL_CHAR    012  /* or char constant? */
        #define M(text,char)    /* unknown macro definition here */

        char a = 012;           /* or a = '\012' */
        const char *b = M("some text with a char ",SPECIAL_CHAR);

I've been only able to do one or the other assignment but not both.  It
seems to boil down to being able to produce the character \ or ' in a
macro without the preprocessor complaining or producing wrong output.

Thanks,

/cc

    #define M(a,b) M1(a,\b)

Trigraph expansion is done every early, in translation phase 1. Backslash
processing is performed in translation phase 2. The following is legal C:

    #define FOO {       ??/
        puts("hello");        ??/
    }

The ??/ have the same effect as backslashes would, causing physical lines to
be folded into logical lines.

The following is a perfectly valid macro definition:

    #define M(a,b) M1(a,\b)

The replacement text is a sequence of tokens, as required. Since the backslash
is not followed immediately by a newline, it is not subject to any special
processing in translation phase 2. A subsequent macro call M("foo ",012)
should result in the single string literal preprocessor token "foo \012".

What compiler are you using? The HP-UX c89 compiler complains about an illegal
backslash if it is not operated in ANSI C mode, but does the right thing when
asked to conform.
--