Può essere utile specificare la piattaforma, la versione di GDB e la sequenza esatta di comandi GDB utilizzati.
Ecco quello che vedo (GDB sembra funzionare bene):
$ gcc -g test.c
$ gdb a.out
GNU gdb (GDB) 6.8.50.20090430-cvs
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-unknown-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
(gdb) list
1 #include <stdio.h>
2 #include <stdlib.h>
3
4 int main(int argc, char** argv){
5 printf("Hello world\n");
6
7 int a = 12;
8 a = 10;
9 return 0;
10 }
11
(gdb) b 5
Breakpoint 1 at 0x4004a7: file test.c, line 5.
(gdb) r
Breakpoint 1, main (argc=1, argv=0x7fffffffdb28) at test.c:5
5 printf("Hello world\n");
(gdb) watch a
Hardware watchpoint 2: a
(gdb) c
Hello world
Hardware watchpoint 2: a
Old value = 0
New value = 12
main (argc=1, argv=0x7fffffffdb28) at test.c:8
8 a = 10;
(gdb) c
Hardware watchpoint 2: a
Old value = 12
New value = 10
main (argc=1, argv=0x7fffffffdb28) at test.c:9
9 return 0;
(gdb) c
Watchpoint 2 deleted because the program has left the block in
which its expression is valid.
0x00007ffff7ab3033 in exit() from /lib/libc.so.6
(gdb) c
Program exited normally.
(gdb) q
fonte
2009-05-09 02:08:03
Hai compilato con le informazioni di debug (-g) e sei sicuro di star usando la versione di debug? – dirkgently