每行打印一个结构体成员

#include <stdio.h>
#include <pthread.h>

typedef struct
{
        int a;
        int b;
        int c;
        int d;
        pthread_mutex_t mutex;
}ex_st;

int main(void) {
        ex_st st = {1, 2, 3, 4, PTHREAD_MUTEX_INITIALIZER};
        printf("%d,%d,%d,%d\n", st.a, st.b, st.c, st.d);
        return 0;
}

技巧

默认情况下，gdb以一种“紧凑”的方式打印结构体。以上面代码为例：

(gdb) n
15              printf("%d,%d,%d,%d\n", st.a, st.b, st.c, st.d);
(gdb) p st
$1 = {a = 1, b = 2, c = 3, d = 4, mutex = {__data = {__lock = 0, __count = 0, __owner = 0, __nusers = 0, __kind = 0,
      __spins = 0, __list = {__prev = 0x0, __next = 0x0}}, __size = '\000' <repeats 39 times>, __align = 0}}

可以看到结构体的显示很混乱，尤其是结构体里还嵌套着其它结构体时。

可以执行“set print pretty on”命令，这样每行只会显示结构体的一名成员，而且还会根据成员的定义层次进行缩进：

(gdb) set print pretty on
(gdb) p st
$2 = {
  a = 1,
  b = 2,
  c = 3,
  d = 4,
  mutex = {
    __data = {
      __lock = 0,
      __count = 0,
      __owner = 0,
      __nusers = 0,
      __kind = 0,
      __spins = 0,
      __list = {
        __prev = 0x0,
        __next = 0x0
      }
    },
    __size = '\000' <repeats 39 times>,
    __align = 0
  }
}

详情参见 gdb手册