Question

I’m looking for a way to convert a preprocessor token to a string.

Specifically, I’ve somewhere got:

#define MAX_LEN 16 

and I want to use it to prevent buffer overrun:

char val[MAX_LEN+1]; // room for \0 sscanf(buf, '%'MAX_LEN's', val); 

I’m open to other ways to accomplish the same thing, but standard library only.

Answer 1

See Using FILE and LINE to Report Errors:

#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);.