带有C程序的GDB问题

$ gcc -g pointer.c
$ gdb -q ./a.out
Reading symbols for shared libraries .. done
(gdb) list
1   #include <stdio.h>
2   #include <string.h>
3   
4   int main() {
5     char str[20];
6     char *pointer;
7   
8     strcpy(str, \"Hello, world!\\n\");
9     pointer = str;
10    printf(\"%s\",pointer);
(gdb) 
11  }
(gdb) break 10
Breakpoint 1 at 0x100000ed1: file pointer.c, line 10.
(gdb) run
Starting program: /Users/___/a.out 
Reading symbols for shared libraries +. done

Breakpoint 1, main () at pointer.c:10
10    printf(\"%s\",pointer);
(gdb) print pointer
$1 = 0x7fff5fbff950 \"Hello, world!\\n\"
(gdb) print &pointer
$2 = (char **) 0x7fff5fbff948
(gdb) x/s 0x7fff5fbff950
0x7fff5fbff950:  \"Hello, world!\\n\"
(gdb) x/16b 0x7fff5fbff950
0x7fff5fbff950:  \"Hello, world!\\n\"
0x7fff5fbff95f:  \"\"
0x7fff5fbff960:  \"x??_?\"
0x7fff5fbff967:  \"\"
0x7fff5fbff968:  \"՝?Y4?K\\033???_?\"
0x7fff5fbff977:  \"\"
0x7fff5fbff978:  \"?\\016\"
0x7fff5fbff97b:  \"\"
0x7fff5fbff97c:  \"\\001\"
0x7fff5fbff97e:  \"\"
0x7fff5fbff97f:  \"\"
0x7fff5fbff980:  \"\"
0x7fff5fbff981:  \"\"
0x7fff5fbff982:  \"\"
0x7fff5fbff983:  \"\"
0x7fff5fbff984:  \"\"
(gdb) x/x 0x7fff5fbff950
0x7fff5fbff950: 0x48
(gdb) x/x 0x7fff5fbff951
0x7fff5fbff951: 0x65
(gdb) x/s 0x7fff5fbff951
0x7fff5fbff951:  \"ello, world!\\n\"
(gdb) print &pointer
$3 = (char **) 0x7fff5fbff948
(gdb) x/x 0x7fff5fbff948
0x7fff5fbff948: 0x00007fff5fbff950
(gdb) x/x 0x7fff5fbff949
0x7fff5fbff949: 0x4800007fff5fbff9
(gdb) x/2x 0x00007fff5fbff950
0x7fff5fbff950: 0x77202c6f6c6c6548  0x00000a21646c726f