C实现日志等级控制

 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <stdarg.h>
 #include <time.h>

 #define SJXC_LOG_DEBUG(level, format, arg...)     SJXC_log_msg_print(level, __FILE__, __func__, __LINE__, format, ##arg)

 #ifdef SJXC_DISABLE_DEBUG
 #define SJXC_REAL_DEBUG_LEVEL    0
 #else
 #define SJXC_REAL_DEBUG_LEVEL    SJXC_DEBUG_LEVEL
 #endif

 #define SJXC_ERROR   (1 << 0)
 #define SJXC_WARN    (1 << 1)
 #define SJXC_INFO    (1 << 2)
 #define SJXC_DEBUG   (1 << 3)

 int SJXC_DEBUG_LEVEL = ;

 struct SJXC_gdb {
     int level;
     const char *msg;
 };

 struct SJXC_gdb SJXC_gdb_table[] = {
     {SJXC_ERROR, "Config the log level as error."},
     {SJXC_WARN, "Config the log level as warn."},
     {SJXC_INFO, "Config the log level as info."},
     {SJXC_DEBUG, "Config the log level as DEBUG."}
 };

 void SJXC_print_debuf_usage(void)
 {
     struct SJXC_gdb *p_gdb;
     fprintf(stderr,
             "    To calculate the debug level, logically 'or'\n"
             "    some of the following values together to get a bebug level:\n");
     for (p_gdb = SJXC_gdb_table; p_gdb < SJXC_gdb_table + (sizeof(SJXC_gdb_table) / sizeof(struct SJXC_gdb)); p_gdb++) {
         fprintf(stderr, "\t%d:\t%s\n", p_gdb->level, p_gdb->msg);
     }
     fprintf(stderr, "\n");
 }

 void SJXC_log_msg_print(int level, const char *file, const char *func, const int line, char *fmt, ...)
 {
     char *status;

     switch (level) {
         case SJXC_ERROR:
             status = "ERROR";
             break;
         case SJXC_WARN:
             status = "WRAN";
             break;
         case SJXC_INFO:
             status = "INFO";
             break;
         case SJXC_DEBUG:
             status = "DEBUG";
             break;
         default:
             printf("Debug message level ERROR!\n");
     }

     if (SJXC_REAL_DEBUG_LEVEL & level) {
         char msg_buf[*];
         char *ascii_time_buf;
         time_t tnow = time(NULL);
         va_list ap;

         ascii_time_buf = asctime(localtime(&tnow));
         ascii_time_buf[strlen(ascii_time_buf) - ] = '\0';

         va_start(ap, fmt);
         sprintf(msg_buf, "    ------> [ %s %s:%s:%d ] %s ", ascii_time_buf, file, func, line, status);
         vsprintf(msg_buf + strlen(msg_buf), fmt, ap);
         fprintf(stderr, "%s\n", msg_buf);
         va_end(ap);
     }
 }

 #if 1
 int main(void)
 {
     int i = ;
     printf("%d\n", SJXC_REAL_DEBUG_LEVEL);
     SJXC_print_debuf_usage();
     while( i != ) {
         SJXC_log_msg_print(SJXC_ERROR, __FILE__, __func__, __LINE__, "");
         i++;
     }
 　　return ;
 }
 #endif