如何在 gdb 中"watch" C++ std：：vector 的大小？

How to "watch" the size of a C++ std::vector in gdb?

本文关键字：vector std C++ gdb watch      更新时间：2023-10-16

我有一个std::vector作为类的一部分，它包含一个自定义类型。它的内容似乎在节目的某个地方被神秘地改变了。我很难弄清楚这是在哪里发生的。

是否有一种方法可以从gdb"观察"std::vector的内容(或大小)?

谢谢。

是否有一种方法可以从gdb"观察"std::vector的内容(或大小)?

假设您正在使用GCC，在theVector->_M_impl._M_start和_M_finish上设置观察点。如果您正在使用其他std::vector实现，请相应地进行调整。

的例子:

#include <vector>
int main()
{
  std::vector<int> v;
  v.push_back(1);
  v.push_back(2);
}
g++ -g t.cc
gdb -q ./a.out
Reading symbols from /tmp/a.out...done.
(gdb) start
Temporary breakpoint 1 at 0x40090f: file t.cc, line 5.
Temporary breakpoint 1, main () at t.cc:5
5     std::vector<int> v;
(gdb) n
7     v.push_back(1);
(gdb) p v._M_impl._M_start
$1 = (int *) 0x0
(gdb) p v._M_impl._M_finish 
$2 = (int *) 0x0
(gdb) p &v._M_impl._M_finish
$3 = (int **) 0x7fffffffd878
(gdb) watch *$3
Hardware watchpoint 2: *$3
(gdb) p &v._M_impl._M_start
$4 = (int **) 0x7fffffffd870
(gdb) watch *$4
Hardware watchpoint 3: *$4
(gdb) c
Hardware watchpoint 3: *$4
Old value = (int *) 0x0
New value = (int *) 0x604010
std::vector<int, std::allocator<int> >::_M_insert_aux (this=0x7fffffffd870, __position=0x0) at /usr/include/c++/4.4/bits/vector.tcc:365
365       this->_M_impl._M_finish = __new_finish;
(gdb) bt
#0  std::vector<int, std::allocator<int> >::_M_insert_aux (this=0x7fffffffd870, __position=0x0) at /usr/include/c++/4.4/bits/vector.tcc:365
#1  0x0000000000400a98 in std::vector<int, std::allocator<int> >::push_back (this=0x7fffffffd870, __x=@0x7fffffffd88c) at /usr/include/c++/4.4/bits/stl_vector.h:741
#2  0x0000000000400935 in main () at t.cc:7
(gdb) c
Hardware watchpoint 2: *$3
Old value = (int *) 0x0
New value = (int *) 0x604014
std::vector<int, std::allocator<int> >::_M_insert_aux (this=0x7fffffffd870, __position=0x0) at /usr/include/c++/4.4/bits/vector.tcc:366
366       this->_M_impl._M_end_of_storage = __new_start + __len;
(gdb) bt
#0  std::vector<int, std::allocator<int> >::_M_insert_aux (this=0x7fffffffd870, __position=0x0) at /usr/include/c++/4.4/bits/vector.tcc:366
#1  0x0000000000400a98 in std::vector<int, std::allocator<int> >::push_back (this=0x7fffffffd870, __x=@0x7fffffffd88c) at /usr/include/c++/4.4/bits/stl_vector.h:741
#2  0x0000000000400935 in main () at t.cc:7
... etc...

我想http://sourceware.org/gdb/wiki/STLSupport会有帮助的。

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