我正在使用 C++ 学习 OOP，但遇到了问题。我确定这是一个内存分配问题，但似乎无法理解它。任何帮助将不胜感激。

我的客户端代码

    #include <iostream>
    #include "Box.cpp"

    using namespace std;

    int main(){
        Box *box = new Box;
        return 0;
    }

我的盒子类...

    #include <iostream>

    using namespace std;

    class Box{

        private:
            double width;
            double height;
            double perimeter;
            double area;


        public:
            Box(){
                cout << "Box created" << endl;
            }

            ~Box(){
                cout << "Box Destroyed" << endl;
            }

            double getWidth(){
                //
                return this->width;
            }

            double getHeight(){
                //
                return this->height;
            }

            double getArea(){
                //
                return this->area;
            }

            double getPerimeter(){
                //
                return this->perimeter;
            }

            void setWidth(double w){
                //
                this->width = w;
                if(!this->height){
                    computeSetArea(this->width, this->height);
                    computeSetPerimeter(this->width, this->height);
                }
            }

            void setHeight(double h){
                //
                this->height = h;
                if(!this->width){
                    computeSetArea(this->width, this->height);
                    computeSetPerimeter(this->width, this->height);
                }
            }

        private:
            void computeSetArea(double w, double h){
                //
                this->area = w*h;
            }

            void computeSetPerimeter(double w, double h){
                //
                this->perimeter = (w * 2) + (h + 2);
            }
    };

我使用 gcc 并执行:

    gcc Box.cpp client.cpp -o mainfile

之后我收到这个错误。

/tmp/ccaVb21k.o: In function `__static_initialization_and_destruction_0(int, int)':
Box.cpp:(.text+0x1d): undefined reference to `std::ios_base::Init::Init()'
Box.cpp:(.text+0x22): undefined reference to `std::ios_base::Init::~Init()'
/tmp/ccaVb21k.o:(.eh_frame+0x12): undefined reference to `__gxx_personality_v0'
/tmp/ccjtbzi4.o: In function `main':
client.cpp:(.text+0x14): undefined reference to `operator new(unsigned int)'
client.cpp:(.text+0x3f): undefined reference to `operator delete(void*)'
/tmp/ccjtbzi4.o: In function `__static_initialization_and_destruction_0(int, int)':
client.cpp:(.text+0x6c): undefined reference to `std::ios_base::Init::Init()'
client.cpp:(.text+0x71): undefined reference to `std::ios_base::Init::~Init()'
/tmp/ccjtbzi4.o: In function `Box::Box()':
client.cpp:(.text._ZN3BoxC1Ev[Box::Box()]+0x11): undefined reference to `std::cout'
client.cpp:(.text._ZN3BoxC1Ev[Box::Box()]+0x16): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)'
client.cpp:(.text._ZN3BoxC1Ev[Box::Box()]+0x1e): undefined reference to `std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)'
client.cpp:(.text._ZN3BoxC1Ev[Box::Box()]+0x26): undefined reference to `std::basic_ostream<char, std::char_traits<char> >::operator<<(std::basic_ostream<char, std::char_traits<char> >& (*)(std::basic_ostream<char, std::char_traits<char> >&))'
/tmp/ccjtbzi4.o:(.eh_frame+0x12): undefined reference to `__gxx_personality_v0'
/tmp/ccjtbzi4.o:(.eh_frame+0x4b): undefined reference to `__gxx_personality_v0'
collect2: ld returned 1 exit status

最佳答案

您的代码编译正常，您遇到链接器错误(ld 是链接器，它返回 1(错误))，这是在提示缺少 c++ 库。

要修复，您需要将 stdc++ 库添加到命令行，或使用 g++。

将 gcc 替换为 g++ 或将 -lstdc++ 添加到您的 gcc 命令行。

gcc Box.cpp client.cpp -o mainfile -lstdc++

或

g++ Box.cpp client.cpp -o mainfile

这会将 std c++ 库与您编译的代码链接起来。使用g++，可以省略这一步。

关于c++ - 对 std::ios_base::Init::Init() 的 undefined reference ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/20010244/