根据http://gcc.gnu.org/onlinedocs/cpp/Variadic-Macros.html， __VA_ARGS__之前应该有##。

否则，宏#define dbg_print(format，…)printf(format， __VA_ARGS__)将不会编译以下示例:dbg_print("hello world");

#define PRINT_LOG(str_format, ...) { \
    time_t curtime=time (NULL); \
    struct tm *ltm = localtime (&curtime); \
    printf("[%d-%02d-%02d %02d:%02d:%02d] " str_format, \
        ltm->tm_year + 1900, ltm->tm_mon + 1, ltm->tm_mday, \
        ltm->tm_hour, ltm->tm_min, ltm->tm_sec, ##__VA_ARGS__); \
}
    
PRINT_LOG("[%d] Serving client, str=%s, number=%d\n", getpid(), "my str", 10);

我会这样做

#ifdef DEBUG
#define debug_print(fmt, ...) fprintf(stderr, fmt, __VA_ARGS__)
#else
#define debug_print(fmt, ...) do {} while (0)
#endif

我觉得这个比较干净。

对于一个可移植的(ISO C90)实现，您可以使用双括号，就像这样;

#include <stdio.h>
#include <stdarg.h>

#ifndef NDEBUG
#  define debug_print(msg) stderr_printf msg
#else
#  define debug_print(msg) (void)0
#endif

void
stderr_printf(const char *fmt, ...)
{
  va_list ap;
  va_start(ap, fmt);
  vfprintf(stderr, fmt, ap);
  va_end(ap);
}

int
main(int argc, char *argv[])
{
  debug_print(("argv[0] is %s, argc is %d\n", argv[0], argc));
  return 0;
}

或者(不推荐)

#include <stdio.h>

#define _ ,
#ifndef NDEBUG
#  define debug_print(msg) fprintf(stderr, msg)
#else
#  define debug_print(msg) (void)0
#endif

int
main(int argc, char *argv[])
{
  debug_print("argv[0] is %s, argc is %d"_ argv[0] _ argc);
  return 0;
}

下面我最喜欢的是var_dump，当它被调用时:

var_dump（“%d”， 计数）;

产生如下输出:

Patch.c:150:main(): count = 0

感谢@“Jonathan Leffler”。所有都是c89快乐的:

Code

#define DEBUG 1
#include <stdarg.h>
#include <stdio.h>
void debug_vprintf(const char *fmt, ...)
{
    va_list args;
    va_start(args, fmt);
    vfprintf(stderr, fmt, args);
    va_end(args);
}

/* Call as: (DOUBLE PARENTHESES ARE MANDATORY) */
/* var_debug(("outfd = %d, somefailed = %d\n", outfd, somefailed)); */
#define var_debug(x) do { if (DEBUG) { debug_vprintf ("%s:%d:%s(): ", \
    __FILE__,  __LINE__, __func__); debug_vprintf x; }} while (0)

/* var_dump("%s" variable_name); */
#define var_dump(fmt, var) do { if (DEBUG) { debug_vprintf ("%s:%d:%s(): ", \
    __FILE__,  __LINE__, __func__); debug_vprintf ("%s = " fmt, #var, var); }} while (0)

#define DEBUG_HERE do { if (DEBUG) { debug_vprintf ("%s:%d:%s(): HERE\n", \
    __FILE__,  __LINE__, __func__); }} while (0)

下面是我使用的版本:

#ifdef NDEBUG
#define Dprintf(FORMAT, ...) ((void)0)
#define Dputs(MSG) ((void)0)
#else
#define Dprintf(FORMAT, ...) \
    fprintf(stderr, "%s() in %s, line %i: " FORMAT "\n", \
        __func__, __FILE__, __LINE__, __VA_ARGS__)
#define Dputs(MSG) Dprintf("%s", MSG)
#endif