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我使用GDB来调试我的代码,并在函数中产生断点时卡住(例如:使用string.h中的strcpy)。使用GDB的断点
1)在这段代码中,gdb停在断点内部的strcpy函数中。
(gdb) list
1 #include<stdio.h>
2 #include<string.h>
3 main()
4 {
5 char a[20],b[]="ffff";
6 strcpy(a,b);
7 printf("%s\n",a);
8 }
(gdb) break 6
Breakpoint 1 at 0x8048486: file thu.c, line 6.
(gdb) break strcpy
Breakpoint 2 at 0x8048370
(gdb) break 7
Breakpoint 3 at 0x804849a: file thu.c, line 7.
(gdb) run
Starting program: /home/m/a.out
Breakpoint 1, main() at thu.c:6
6 strcpy(a,b);
(gdb) c
Continuing.
Breakpoint 2, 0xb7ea2490 in ??() from /lib/i386-linux-gnu/libc.so.6
(gdb) c
Continuing.
Breakpoint 3, main() at thu.c:7
7 printf("%s\n",a);
你可以看到gdb停在breakpoint2(在strcpy里面)。
2)在这段代码中,GDB不是停在断点2(在strcpy内部),而是到断点3。
(gdb) list
1 #include<stdio.h>
2 #include<string.h>
3 main()
4 {
5 char a[20];
6 strcpy(a,"hello world!");
7 printf("%s\n",a);
8 }
(gdb) break 6
Breakpoint 1 at 0x8048449: file thu.c, line 6.
(gdb) break strcpy
Function "strcpy" not defined.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 2 (strcpy) pending.
(gdb) break 7
Breakpoint 3 at 0x8048469: file thu.c, line 7.
(gdb) run
Starting program: /home/m/a.out
Breakpoint 1, main() at thu.c:6
6 strcpy(a,"hello world!");
(gdb) c
Continuing.
Breakpoint 3, main() at thu.c:7
7 printf("%s\n",a);
那么是什么让两种情况不同呢? 我跟着书“黑客:开发的艺术”Jon Erickson,这是本书的一个例子,案例2与代码char_array2.c在39页相似,但输出与案例中的书不相似的断点2.
感谢您的阅读!