我现在正在使用 Bruce Eckel 的“Thinking in C++”学习 C++,并且我在学习前面几章。我有 C 和 Java 背景。现在我遇到了以下问题:当我用
编译下面的源代码时g++ A.cpp B.cpp bmain.cpp
,程序输出“1”(正确),然后是段错误。当我编译时
g++ -g A.cpp B.cpp bmain.cpp
,完全相同的程序产生 1 且没有段错误!我不得不说我发现这令人惊讶。有人可以指出我做错了什么吗?我的操作系统是“Linux 2.6.35-30-generic#54-Ubuntu x86_64”,我的 g++ 版本是“g++ (Ubuntu/Linaro 4.4.4-14ubuntu5) 4.4.5”。
编辑:仅仅因为这似乎是错误的重要来源,感谢@Evan Teran:永远不会调用 B 结构中的 A 构造函数!我放了一个“cout << “blah” << endl;”里面,它不打印任何东西
编辑:我现在在 main 的末尾包含了“return 0”,但这没有帮助。
嗯:
#ifndef A_H
#define A_H
#include <string>
class A {
public:
int i;
std::string str;
void print();
A();
};
#endif
A.cpp:
#include "A.h"
#include <iostream>
#include <string>
using namespace std;
void A::print() {
cout << str << " " << i << endl;
}
A::A() {
str = "initstr";
i = 0;
}
B.h:
#ifndef B_H
#define B_H
#include "A.h"
class B {
private:
int counter;
public:
A a;
B();
void increase();
int read();
};
#endif
B.cpp:
#include "B.h"
using namespace std;
B::B() {
counter = 0;
}
void B::increase() {
++counter;
}
int B::read() {
return counter;
}
bmain.cpp:
#include <iostream>
#include "B.h"
using namespace std;
int main(int argc, char **argv) {
B b;
b.increase();
cout << b.read() << endl;
return 0;
}
编辑:我已经从软件包中安装了 g++。我的 Ubuntu 也很标准。
这是我打电话时得到的 gdb a.out 核心
warning: Can't read pathname for load map: Eingabe-/Ausgabefehler.
Reading symbols from /usr/lib/libstdc++.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libstdc++.so.6
Reading symbols from /lib/libm.so.6...Reading symbols from /usr/lib/debug/lib/libm-2.12.1.so...done.
done.
Loaded symbols for /lib/libm.so.6
Reading symbols from /lib/libgcc_s.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/libgcc_s.so.1
Reading symbols from /lib/libc.so.6...Reading symbols from /usr/lib/debug/lib/libc-2.12.1.so...done.
done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /lib64/ld-linux-x86-64.so.2...Reading symbols from /usr/lib/debug/lib/ld-2.12.1.so...done.
done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
Core was generated by `./a.out'.
Program terminated with signal 11, Segmentation fault.
#0 0x00007fba1049104b in std::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string() () from /usr/lib/libstdc++.so.6
编辑 2: 顺便说一句,据我所知,我的硬件没有故障,我对操作系统的处理也很好
编辑 3: Valgrind 报告如下:
==3428== Conditional jump or move depends on uninitialised value(s)
==3428== at 0x4ECB022: std::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string() (in /usr/lib/libstdc++.so.6.0.14)
==3428== by 0x400D73: A::~A() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428== by 0x400D91: B::~B() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428== by 0x400CD7: main (in /home/xxx/C++/Exercises/ch04/a.out)
==3428==
==3428== Use of uninitialised value of size 8
==3428== at 0x4ECB04B: std::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string() (in /usr/lib/libstdc++.so.6.0.14)
==3428== by 0x400D73: A::~A() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428== by 0x400D91: B::~B() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428== by 0x400CD7: main (in /home/xxx/C++/Exercises/ch04/a.out)
==3428==
==3428== Invalid read of size 4
==3428== at 0x4ECB04B: std::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string() (in /usr/lib/libstdc++.so.6.0.14)
==3428== by 0x400D73: A::~A() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428== by 0x400D91: B::~B() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428== by 0x400CD7: main (in /home/xxx/C++/Exercises/ch04/a.out)
==3428== Address 0xfffffffffffffff8 is not stack'd, malloc'd or (recently) free'd
==3428==
==3428==
==3428== Process terminating with default action of signal 11 (SIGSEGV): dumping core
==3428== Access not within mapped region at address 0xFFFFFFFFFFFFFFF8
==3428== at 0x4ECB04B: std::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string() (in /usr/lib/libstdc++.so.6.0.14)
==3428== by 0x400D73: A::~A() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428== by 0x400D91: B::~B() (in /home/xxx/C++/Exercises/ch04/a.out)
==3428== by 0x400CD7: main (in /home/xxx/C++/Exercises/ch04/a.out)
==3428== If you believe this happened as a result of a stack
==3428== overflow in your program's main thread (unlikely but
==3428== possible), you can try to increase the size of the
==3428== main thread stack using the --main-stacksize= flag.
==3428== The main thread stack size used in this run was 8388608.
==3428==
==3428== HEAP SUMMARY:
==3428== in use at exit: 0 bytes in 0 blocks
==3428== total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==3428==
==3428== All heap blocks were freed -- no leaks are possible
最佳答案
按照这种方式,它似乎是 GCC/libstdc++ 打包/构建或所用版本中的错误。试试 GCC 4.5 或 4.6,如果没有,请告诉自己始终使用最新和最好的(当然直到它破坏某些东西)并且永远不要回头。
似乎编译器没有初始化 B
中的 A
成员,这将导致 std::string
的析构函数失败阅读必要的信息以正确销毁自身。但这只是推测和猜测。
关于c++ - g++ 在正常编译时会产生段错误,但在 -g 时不会,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/6707730/