#define DEBUG(fmt,expr) \
fprintf(stderr, "DEBUG: " __FILE__ ":%d - " #expr " = [" #fmt "]\n", __LINE__, expr);
##</code><code>##

10: char szMyString[] = "ContentsOfMyString";
31: ...
32: DEBUG(%s, szMyString);
33: ...
34: ...
... output =>
DEBUG: my_script.c:32: - szMyString = [ContentsOfMyString]