Xem dữ liệu: print, x và ptype

(gdb) print a
$1 = {5, 3, 9, 1, 7}          /* mang co kich thuoc biet truoc: in het */

(gdb) print a[0]@5
$2 = {5, 3, 9, 1, 7}          /* cu phap @: in n phan tu tu mot dia chi */

(gdb) print *p@10             /* voi con tro: day la cach DUY NHAT */
(gdb) print *ds@so_phan_tu    /* so luong lay tu mot bien */

/* Cu phap @ la thu quan trong nhat trong muc nay:
   voi "int *p = malloc(n * sizeof *p)", GDB khong biet n,
   nen "print p" chi cho ra dia chi va "print *p" chi cho phan tu dau. */

# Mang lon: gioi han so phan tu in ra
(gdb) show print elements
Limit on string chars or array elements to print is 200.

(gdb) set print elements 0          # khong gioi han
(gdb) set print elements 20         # chi 20 phan tu dau

# In dep hon
(gdb) set print array on            # moi phan tu mot dong
(gdb) set print array-indexes on    # kem chi so

(gdb) print a
$1 = {[0] = 5,
      [1] = 3,
      [2] = 9,
      [3] = 1,
      [4] = 7}

# Gom cac gia tri giong nhau
(gdb) show print repeats
Threshold for repeated print elements is 10.

(gdb) print bo_dem
$2 = '\000' <repeats 1023 times>    # thay vi in 1024 so khong

(gdb) ptype Nut          /* dinh nghia DAY DU cua kieu */
(gdb) ptype dau          /* kieu cua bien, dau * o cuoi cho biet la con tro */
(gdb) whatis dau         /* chi TEN kieu, khong khai trien */
$1 = type = Nut *

(gdb) ptype tong         /* ca chu ky ham */
type = int (const Nut *)

(gdb) ptype/o Nut        /* GDB 8.1 tro len: kem OFFSET va kich thuoc */

# Ba lenh info tra cuu ky hieu

(gdb) info functions tong        # moi ham co ten chua "tong"
All functions matching regular expression "tong":

File dslk.c:
static int tong(const Nut *);

(gdb) info variables              # moi bien toan cuc va tinh
(gdb) info types Nut              # moi kieu khop
(gdb) info line dslk.c:23         # dia chi cua mot dong
(gdb) info symbol 0x4015be        # ky hieu tai mot dia chi
(gdb) info scope tong             # bien nao song trong ham tong

display x                 # in x sau MOI lan dung
display/x co              # kem dinh dang
display *p                # theo doi thu con tro tro toi
info display              # liet ke
undisplay 1               # bo mot cai
delete display            # bo het

/* display la thu bien viec buoc tung dong thanh de chiu:
   thay vi go "print x" sau moi lenh next, ban dang ky mot lan
   va GDB in tu dong. */

set var x = 100                 # sua bien
set var p->ma = 5               # sua truong qua con tro
set var a[2] = 42               # sua phan tu mang
set var s[0] = 'A'              # sua ky tu

set var $rax = 0                # sua thanh ghi

call ham(1, 2)                  # goi mot ham
print ham(1, 2)                 # giong call nhung in ket qua

return                          # ep ham hien tai tra ve NGAY
return 0                        # tra ve voi gia tri 0

jump 42                         # nhay toi dong 42, KHONG chay cac dong giua