vsnprintf日志中打印程序名和行号实例

#define FILENAME_LEN 100
#define MAXLINE 1024
#define MAXBYTES 50

static char c_FileName[FILENAME_LEN];
static int  i_FileLineNum;

//Self-define a function which can print the name and line-number of the source file calling it.
#define PRINT Get_File_Line( __FILE__, __LINE__ );\
              F_vsnprintf

/**
 * Get the linenum and filename of the source file.
 * @Para-in:        p_FileName: The name of the source file.
 * @Para-in:        i_FileLine: The line-number of the source file.
 */
void Get_File_Line( char *p_FileName, int i_FileLine )
{
    strcpy( c_FileName, p_FileName );
    i_FileLineNum = i_FileLine;
    return;
}

/**
 * Print the arguments according to the first argument, name as fmt.
 */
void F_vsnprintf( char *fmt, ... )
{
    char buf[MAXLINE] = {0x00};
    snprintf( buf, MAXBYTES, "[%s:%d] ", c_FileName, i_FileLineNum );
    va_list ap;
    va_start( ap, fmt );
    vsnprintf( buf+strlen(buf), MAXLINE, fmt, ap );
    va_end( ap );

    strcat( buf, "\n" );
    fflush( stdout );

    fputs( buf, stderr );
    fflush( NULL );
    return;
}

int main( int argc, char **argv )
{
    PRINT( "[%s]", "Hello." );
    PRINT( "[%s %s]", "Hello", "world." );
    return 0;
}