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In article <1qcc03$gl3@genesis.ait.psu.edu> sba@astro.psu.edu (Stuart Anderson) writes:
>How does one concatenate strings with the gnu-cpp?

Your question should read "How does one concatenate strings with any
ANSI C compiler?"
>
>Example, I would like the output of the following macro to read
>"calling the fortran subroutine time_"
> *** NOT ***
>"calling the fortran subroutine func"
>(note: the Sun cpp does this OK)

The unbundled Sun cpp is a so called "Reiser" C preprocessor (e.g. broken
according to the ANSI C standard).

Here's what you need to know about ANSI C:

First, two adjacent strings are always concatenated: e.g.
"hello " "world"
is the same as "hello world".

Second, the preprocessor does not expand macro arguments inside quotes:
#define foo(arg) "arg"

returns "arg" no matter what the argument is.

There are two operators that may be used in macro definitions: the
stringize operator # and the token concatenation operator ##.  The
following Reiser preprocessor trick

#define PASTE(x,y) x/**/y

is illegal according to ANSI -- instead you write

#define PASTE(x,y) x ## y

Back to your request: you want to paste an underscore to the end of
your argument, and you want to end up with a single string.

To paste on the underscore you could say.

#define FORTRAN(func) func ## _

Now, you cannot say

"Calling the fortran subroutine FORTRAN(time)"

since macros are not expanded inside quotes.  Instead you could say

#define STR(func) #func
#define CALLING_FORTRAN(func) "Calling the fortran subroutine " STR(func) "_"

If you view the C preprocessor output this will look like three strings,
but it can be used as a single string.

These rules are obeyed by all ANSI C preprocessors.  Unfortunately, K&R
C preprocessors are quite different.


--
Joe Buck	jbuck@ohm.berkeley.edu