Question

这是我的错误类来处理错误与try＆amp;赶上：

#include <stdexcept>
#include <string>

  class Error : public std::exception
    {
    public:
      Error(const std::string&) throw();
      ~Error() throw();
      const char*   what() const throw();
    private:
      std::string           _msg;
    };

和cpp文件：

#include "Error.hpp"

Error::Error(const std::string& msg) throw()
  : _msg(msg)
{
}

Error::~Error() throw()
{
}

const char*     Error::what() const throw()
{
  return (_msg.c_str());
}

编译时我有这个错误：

main.o:(.gcc_except_table+0x34): undefined reference to `typeinfo for Error'
MailBox.o: In function `MailBox::MailBox(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)':
MailBox.cpp:(.text+0x245): undefined reference to `Error::Error(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
MailBox.cpp:(.text+0x268): undefined reference to `Error::~Error()'
MailBox.cpp:(.text+0x270): undefined reference to `typeinfo for Error'
MailBox.cpp:(.text+0x2f0): undefined reference to `Error::Error(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
MailBox.cpp:(.text+0x313): undefined reference to `Error::~Error()'
MailBox.cpp:(.text+0x31b): undefined reference to `typeinfo for Error'
MailBox.cpp:(.text+0x3d6): undefined reference to `Error::Error(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
MailBox.cpp:(.text+0x3f9): undefined reference to `Error::~Error()'
MailBox.cpp:(.text+0x401): undefined reference to `typeinfo for Error'
MailBox.cpp:(.text+0x452): undefined reference to `Error::Error(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
MailBox.cpp:(.text+0x475): undefined reference to `Error::~Error()'
MailBox.cpp:(.text+0x47d): undefined reference to `typeinfo for Error'
MailBox.cpp:(.text+0x50a): undefined reference to `Error::Error(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
MailBox.cpp:(.text+0x52d): undefined reference to `Error::~Error()'
MailBox.cpp:(.text+0x535): undefined reference to `typeinfo for Error'
MailBox.cpp:(.text+0x6af): undefined reference to `Error::Error(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
MailBox.cpp:(.text+0x6d2): undefined reference to `Error::~Error()'
MailBox.cpp:(.text+0x6da): undefined reference to `typeinfo for Error'
MailBox.cpp:(.text+0x854): undefined reference to `Error::Error(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
MailBox.cpp:(.text+0x877): undefined reference to `Error::~Error()'
MailBox.cpp:(.text+0x87f): undefined reference to `typeinfo for Error'
MailBox.cpp:(.text+0x923): undefined reference to `Error::Error(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
MailBox.cpp:(.text+0x946): undefined reference to `Error::~Error()'
MailBox.cpp:(.text+0x94e): undefined reference to `typeinfo for Error'
MailBox.cpp:(.text+0x9b6): undefined reference to `Error::Error(std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)'
MailBox.cpp:(.text+0x9d9): undefined reference to `Error::~Error()'
MailBox.cpp:(.text+0x9e1): undefined reference to `typeinfo for Error'
collect2: ld returned 1 exit status

我已经将此Error类用于另一个项目，并且运行良好。我不明白为什么在这里它不起作用。

Answer 1

这是不编译错误，这是链接器错误。基本上，此错误通知您缺少某些功能的定义。

从链接器的输出中读取，显然这些函数是类Error的复制构造函数和析构函数。

这与您只显示这些函数的声明（在Error的类定义中）这一事实兼容。您还应该为它们提供定义。例如，您可以简单地内联这些定义：

class Error : public std::exception
{
public:
    Error(const std::string& s) throw() : _msg(s) { }
    ~Error() throw() { };
    const char*   what() const throw() { return _msg.c_str(); };
private:
    std::string _msg;
};

C ++ - 继承自std :: exception的Error类的编译错误

1 个答案: