打印enum变量的段错误

   今天看第三章《数据》，定义了一个枚举类型，打印出来竟然是：Segmentation fault
于是用gdb调试了一下，发现错误出在printf下：
[root@bjxdurs235 c-study]# gdb enum_declaration
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This GDB was configured as "i386-redhat-linux-gnu"...Using host libthread_db library "/lib/tls/libthread_db.so.1".

(gdb) l 1
1       #include
2       int main(void)
3       {
4               /* example 1
5                  enum MONNEY { ONE=1, TWO, FIVE=5, TEN=10 };
6                  printf("TWO:%d",TWO);
7                */
8
9               enum Liquid { OUNCE = 1, CUP = 8, PINT =16,
10                      QUART =32, GALLON = 128 };
(gdb)
11              enum Liquid jar;
12              jar = QUART;
13              printf("jar:%s\n",jar);
14              jar = jar + PINT;
15              printf("jar:%s\n",jar);
16
17      }
(gdb)
Line number 18 out of range; enum_declaration.c has 17 lines.
(gdb) start
Breakpoint 1 at 0x8048384: file enum_declaration.c, line 12.
Starting program: /home/liufeng/c-study/enum_declaration
main () at enum_declaration.c:12
12              jar = QUART;
(gdb) i locals
jar = 7052448
(gdb) p QUART
$1 = QUART
(gdb) n
13              printf("jar:%s\n",jar);
(gdb) p jar
$2 = QUART
(gdb) i locals
jar = QUART
(gdb) p QUART
$3 = QUART
(gdb) n

Program received signal SIGSEGV, Segmentation fault.
0x00729e53 in strlen () from /lib/tls/libc.so.6
   看了课后的答案知道了不能用%s打印，晕倒了，但是不明白为什么我p jar的时候出来的是QUART哦，哦，知道了，QUART被当成了命名常量了吧，改用%d %c打印就没有问题了：

[root@bjxdurs235 c-study]# vi enum_declaration.c

#include
int main(void)
{
        /* example 1
           enum MONNEY { ONE=1, TWO, FIVE=5, TEN=10 };
           printf("TWO:%d",TWO);
         */

        enum Liquid { OUNCE = 1, CUP = 8, PINT =16,
                QUART =32, GALLON = 128 };
        enum Liquid jar;
        jar = QUART;
        printf("jar:%d\n",jar);
        jar = jar + PINT;
        printf("jar:%c\n",jar);

}
~                                                                                                                                  
~                                                                                                                                                                                                                                                     
~                                                                                                                                  
"enum_declaration.c" 17L, 307C written                                                                           
[root@bjxdurs235 c-study]# gcc enum_declaration.c
[root@bjxdurs235 c-study]# ./a.out
jar:32
jar:0

    这个小小的简单程序学会了枚举类型的用法：
enum ENUM_type { a , b , c ,d};
enum ENUM_type i;
i = b;
这样来用，而且a，b，c，d都可以直接使用，类似这样吧：
#define a 0
#define b 1
...