Question

I’m writing a simple macro to show TRACE information.

This is what I’m using ,

#ifdef __DEBUG__
#define TRACE  { PrintErrorMsg("Trace exception at " __FILE__  "LineNo:"##(__LINE__) "Function: " __FUNCTION__ " " );}
#else 
#define TRACE 
#endif

This is working with FILE, but it doesn’t seems to work with LINE ,
Any idea how could I deal with this. I already tried stringing operator too.Which is as
bellow.

#ifdef __DEBUG__
#define TRACE  { PrintErrorMsg("Trace exception at " __FILE__  "LineNo:"#(__LINE__) "Function: " __FUNCTION__ " " );}
#else 
#define TRACE 
#endif

and without parms and with double parms , ex – __LINE__ or ((__LINE__))
Any idea how could I deal with this problem?

And I come up with this,

#ifdef __DEBUG__
#define ERROR_MSG_BUF_SIZE 1024
#define TRACE  { char * error_msg_buffer = new char[ERROR_MSG_BUF_SIZE]; \
                 sprintf(error_msg_buffer,"Trace Exception at file: %s ,Line : %d , Function %s \n",__FILE__,__LINE__,__FUNCTION__);\
PrintErrorMsg(error_msg_buffer );\
delete[] error_msg_buffer;}
#else 
#define TRACE 

But I want to do it without using sprintf , just only by stringing and token pasting.
Any idea?

#endif

–Thanks in advance–

Answer 1

You need this kind of silliness, unfortunately.

#include <stdio.h>

#define TRACE2(f,l) printf("I am at file: " f " and line: " #l "\n")
#define TRACE1(f,l) TRACE2(f,l)
#define TRACE() TRACE1(__FILE__, __LINE__)

int main(void)
{
    TRACE();
    TRACE();
}

I am at file: test.cpp and line: 9
I am at file: test.cpp and line: 10