Duanxx C ++: Use _ FILE __,__ LINE __,__ VA_ARGS _ to debug the code, duanxx _ file __

Duanxx C ++: Use _ FILE __,__ LINE __,__ VA_ARGS _ to debug the code, duanxx _ file __
_ FILE __,__ LINE __

What we want to know most when debugging C/C ++ code is, of course, the number of lines of the file to which the program is currently going. There are two macros: __file _ and _ LINE __, return the path of the current FILE and the current row.

 

The test code is as follows:

#include <cstdio>int main(){  printf("%s : %d",__FILE__,__LINE__);  printf("\n");  return 0;}

The running result in Windows is:

The running result of Linux is as follows:

In Windows, __file _ returnsFull pathIn Linux, if g ++ is used for compiling, onlyFile Name.

_ VA_ARGS __

This is a variable parameter macro supported since C99. Previously, in C language, only variable parameters of functions are supported.

For example, the most common printf function:

void printf(const char* format, …);

Ellipsis ..., YesVariable parameters.

 

The macro _ VA_ARGS _ is a variable parameter that implements the macro:

#define debug(…) printf(__VA_ARGS__)

The test code is as follows:

#include <cstdio>#define DEBUG(...) printf(__VA_ARGS__)int main(){  DEBUG("duanxx %d\n",123);  return 0;}

Running results in Windows:

Running result in Linux:

One row debugging macro

With the above description, you can write the following debugging macro:

#define DEBUG(fmt, ...) \  fprintf(stdout, "%s:%d Duanxx Debug   " fmt "\n", __FILE__, __LINE__, ##__VA_ARGS__)

Test code:

#include <cstdio>#define DEBUG(fmt, ...) \  fprintf(stdout, "%s:%d Duanxx Debug   " fmt "\n", __FILE__, __LINE__, ##__VA_ARGS__)int main(){  DEBUG("duanxx %d\n",123);  return 0;}

Windows results:

Result in Linux:

In C, how does one use _ FILE _ and _ LINE _?

Note: It is a double underline, not a single underline.

_ FILE _ string containing the current program FILE name
_ LINE _ indicates the integer of the current row number.
_ DATE _ string containing the current DATE
_ STDC _ If the compiler complies with the ansi c standard, it is a non-zero value.
_ TIME _ string containing the current TIME

For example:

Program that outputs the current program file name:

//---------------------------------------------------------------------------

# Include <stdio. h>

Int main (void)
{
Printf ("% s" ,__ FILE __);
Return 0;
}
//---------------------------------------------------------------------------

C language _ VA_ARGS _

_ VA_ARGS _ is to directly convert the... in brackets into the actual string. USE_FEATURE_REMOTE_LOG (OPTBIT_remote,) is equal to OPTBIT_remote.

Your printf error occurs. Check whether the position of your printf is not defined by OPTBIT_remote.