Convert a preprocessor token to a string
I found an answer online.
#define VERSION_MAJOR 4 #define VERSION_MINOR 47 #define VERSION_STRING "v" #VERSION_MAJOR "." #VERSION_MINOR
The above does not work but hopefully illustrates what I would like to do, i.e. make VERSION_STRING end up as "v4.47".
To generate the proper numeric form use something like
#define VERSION_MAJOR 4 #define VERSION_MINOR 47 #define STRINGIZE2(s) #s #define STRINGIZE(s) STRINGIZE2(s) #define VERSION_STRING "v" STRINGIZE(VERSION_MAJOR) \ "." STRINGIZE(VERSION_MINOR) #include <stdio.h> int main() { printf ("%s\n", VERSION_STRING); return 0; }
see http://www.decompile.com/cpp/faq/file_and_line_error_string.htm specifically:
#define STRINGIFY(x) #x
#define TOSTRING(x) STRINGIFY(x)
#define AT __FILE__ ":" TOSTRING(__LINE__)
so your problem can be solved by doing
sscanf(buf, "%" TOSTRING(MAX_LEN) "s", val);
It's been a while, but this should work:
sscanf(buf, "%" #MAX_LEN "s", val);
If not, it'll need to "double expansion" trick:
#define STR1(x) #x
#define STR(x) STR1(x)
sscanf(buf, "%" STR(MAX_LEN) "s", val);