You need to stringize TYPECODE twice, or you'll get (as you are
presently) #TYPECODE:
#define STRING2(a) STRING(a)
#define STRING(a) #a
...
snprintf(fname, FILENAME_MAX, "%s_vector.%03d",
STRING2(TYPECODE), filenum++);
...
John G
On Wed, May 11, 2011 at 7:41 PM, Adam Mercer <ramercer@xxxxxxxxx> wrote:
> Hi
>
> I'm trying to write a code that has several functions that are, more
> or less, the same and only differ in the datatype on which they
> operate. To minimise code duplication I'm trying to accomplish this
> using the preprocessor and it's more or less working but I'm having
> problems with one of the functions. The actual code is quite
> complicated but I've reproduced the issue with a simple test code as
> follows:
>
> $ cat test.c
> #include <stdio.h>
>
> #define TYPECODE I8
> #include "test_source.c"
> #undef TYPECODE
>
> int main()
> {
> I8_test();
> return 0;
> }
> $ cat test_source.c
> #define CONCAT2x(a,b) a##b
> #define CONCAT2(a,b) CONCAT2x(a,b)
> #define STRING(a) #a
> #define FUNC CONCAT2(TYPECODE,_test)
>
> int FUNC()
> {
> static int filenum=0;
> char fname[FILENAME_MAX];
> snprintf(fname, FILENAME_MAX, "%s_vector.%03d", \
> STRING(TYPECODE), filenum++);
> printf("%s: %s\n", __func__, fname);
> return 0;
> }
> $ gcc test.c
> $ ./a.out
> I8_test: TYPECODE_vector.000
> $
>
> The problem is that I need the output of the code to be
>
> I8_test: I8_vector.000
>
> Looking at the output from cpp it seems like it should be doing the right thing:
>
> int I8##_test()
> {
> static int filenum=0;
> char fname[1024];
> snprintf(fname, 1024, "%s_vector.%03d", #I8, filenum++);
> printf("%s: %s\n", __func__, fname);
> return 0;
> }
>
> But something is clearly wrong. Can anyone see what I'm doing wrong?
>
> Cheers
>
> Adam
>
