# GDB Inspecting Memory

**Memory inspection** dumps raw bytes at addresses. The `x` command (examine) shows bytes in various formats. Useful for inspecting memory layout, stack contents, or raw pointer data.

```bash
(gdb) x/10x &variable           # show 10 hex values at address of variable
(gdb) x/10i $pc                 # show 10 instructions at program counter
(gdb) x/20x $sp                 # show 20 hex words on stack
(gdb) x/s ptr                   # print string at pointer
(gdb) x/d &x                    # show value at address (decimal)
(gdb) print sizeof(int)         # size of type
(gdb) print sizeof(arr)         # size of array
(gdb) print (char *)ptr         # cast and print
```

The `x` syntax is `x/[count][format] address`. Count is how many units to show (default 1). Format codes:

- `x` — hexadecimal
- `d` — decimal (signed)
- `u` — decimal (unsigned)
- `i` — disassemble as instructions
- `s` — C-string (null-terminated)
- `c` — single character
- `f` — floating-point

The unit size depends on format: `x` shows words (4 bytes by default on 32-bit, 8 on 64-bit); `i` shows full instructions; `s` reads until null terminator. Prefix format with size modifier: `b` (byte), `h` (halfword / 2 bytes), `w` (word / 4 bytes), `g` (giant / 8 bytes). Example: `x/10bx` shows 10 bytes in hex.

`$pc` (program counter) and `$sp` (stack pointer) are special registers. `&variable` gives the address of a local variable. Examine stack to see function arguments and return addresses; examine code memory to see instructions at an address.

`sizeof()` returns the byte size of a type or variable—useful for calculating array sizes or understanding structure layout.