内存分配数据不对

#include <stdio.h>

int main() {

char str[] = "hello";

char *str2 = "world";

char str3[10];

printf("input a value\n");

scanf("%s", str);

//str[3] = '\0';

printf("str is %s\n", str);

printf("str2 is %s\n", str2);

printf("str3 is %s\n", str3);

return 0;

}

下面是调试过程：

Temporary breakpoint 1, main () at main.c:3

3 int main() {

(gdb) n

5 char str[] = "hello";

(gdb) 

6 char *str2 = "world";

(gdb) 

10 printf("input a value\n");

(gdb) 

input a value

11 scanf("%s", str);

(gdb) 

aaaaaaaaaaaaaaaaaaaa

14 printf("str is %s\n", str);

(gdb) p &str

$1 = (char (*)[6]) 0x7fffffffdb00

(gdb) p &str2

$2 = (char **) 0x7fffffffdaf8

(gdb) p &str3

$3 = (char (*)[10]) 0x7fffffffdb10

(gdb) p strt

No symbol "strt" in current context.

(gdb) p str

$4 = "aaaaaa"

(gdb) p str3

$5 = "aaaa\000\000\000\000P\005"

str 是6个字节，无论我怎么输入，str打印出来的都是6个字节，并不是实际长度，还有就是为什 str 和 str3 的内存之间相差的是16个字节，而不是6个呢，str 的地址是 0x7fffffffdb00 , 而 str3 的地址是 0x7fffffffdb10