C language sizeof seeking structure array length

#include <stdio.h>

typedef struct ss{
	char a;//偏移量为0，大小为1,0能被1整除，=1
	short b;//偏移量为1，大小为2,1不能被2整除，=1+1+2=4
	int c;//偏移量为4，大小为4,4能被4整除，=4+4=8
	long d;//偏移量为8，大小为4,8能被4整除，=8+4=12
} ss_t;
struct ss s1[]={
	{0x1,0x2,0x3,0x4},
	{0x5,0x6,0x7,0x8},
	{0xa,0xb,0xc,0xd},
};
int s1_len= sizeof(s1)/sizeof(s1[0]);
struct ss s2[]={
	{0x1,0x2,0x3,0x4},
	{0x5,0x6,0x7,0x8},
	{0xa,0xb,0xc,0xd},
	{},
};
int s2_len= sizeof(s2)/sizeof(s2[0]);
struct ss s3[]={
	{},
	{0x1,0x2,0x3,0x4},
	{0x5,0x6,0x7,0x8},
	{0xa,0xb,0xc,0xd},
};
int s3_len= sizeof(s3)/sizeof(s3[0]);
int main()
{
   /* 我的第一个 C 程序 */
   printf("sizeof(s1)=%d, szieof(s1[0])=%d, s1_len=%d \n", sizeof(s1), sizeof(s1[0]), s1_len);
   printf("sizeof(s2)=%d, szieof(s2[0])=%d, s2_len=%d \n", sizeof(s2), sizeof(s2[0]), s2_len);
   printf("sizeof(s3)=%d, szieof(s3[0])=%d, s3_len=%d \n", sizeof(s3), sizeof(s3[0]), s3_len);
   return 0;
}