4

一个简单的 vector.push_back() 在我的代码中导致一些错误：

#include <vector>
using namespace std;

int main(int argc, const char *argv[])
{
    vector<unsigned> stack;
    stack.push_back(1);
    stack.push_back(1); //stack.size() becomes 467369971 after this
    stack.push_back(1);
    stack.push_back(1);
    ... more push_back()s ...
    return 0;
}

我正在使用 GDB 来检查它的行为……奇怪的是 stack.size() 在第二个 push_back() 之后出错了。变成467369971！可能有什么问题？我在 Win7 64 位上，我正在使用带有 G++ 4.7.0 的 MinGW

下面是 GDB 的输出：

(gdb) n
5                       std::vector<unsigned> sta
(gdb) n
6                       stack.push_back(1);
(gdb) display stack.size()
1: stack.size() = 0
(gdb) n
7                       stack.push_back(1);
1: stack.size() = 1
(gdb)
8                       stack.push_back(1);
1: stack.size() = 467369971 //goes wrong here
(gdb)
9                       stack.push_back(1);
1: stack.size() = 467369971
(gdb)
10                      stack.push_back(1);
1: stack.size() = 4         // gets "normal"
(gdb)
11                      stack.push_back(1);
1: stack.size() = 467369971 // wrong again
(gdb)
12                      stack.push_back(1);
1: stack.size() = 6
(gdb)
13                      stack.push_back(1);
1: stack.size() = 7
(gdb)
14                      stack.push_back(1);
1: stack.size() = 8
(gdb)
15                      stack.push_back(1);
1: stack.size() = 467369971
(gdb)
16                      stack.push_back(1);
1: stack.size() = 10
(gdb)
17                      stack.push_back(1);
1: stack.size() = 11
(gdb)
18                      stack.push_back(1);
1: stack.size() = 12
(gdb)
19                      return 0;
4

1 回答 1

4

可能有什么问题？

这是您的编译器或 GDB 中的错误。它不会在g++ (Ubuntu 4.4.3-4ubuntu5.1) 4.4.3使用GDB 7.4的 Linux 上重现：

(gdb) n
7       stack.push_back(1);
1: stack.size() = 0
(gdb) 
8       stack.push_back(1); //stack.size() becomes 467369971 after this
1: stack.size() = 1
(gdb) 
9       stack.push_back(1);
1: stack.size() = 2
(gdb) 
10      stack.push_back(1);
1: stack.size() = 3
(gdb) 
11      stack.push_back(1);
1: stack.size() = 4
(gdb) 
12      stack.push_back(1); //stack.size() becomes 467369971 after this
1: stack.size() = 5
(gdb) 
13      stack.push_back(1);
1: stack.size() = 6
(gdb) 
14      stack.push_back(1);
1: stack.size() = 7
(gdb) 
15      return 0;
1: stack.size() = 8
(gdb) 
16  }
(gdb) q

不幸的是，要找出应该归咎于哪个工具会有些困难：您需要检查生成的调试信息。相反，您可以尝试使用不同版本的 GCC 和 GDB 重现该问题。如果不同的 GCC 导致错误消失，则可能是 GCC 中的错误。如果不同的 GDB 版本使该错误消失，则可能是 GDB 错误。

于 2012-09-15T23:22:31.507 回答