c ++将一个类定义到另一个类

Question

我试图解决我在c ++中关于类的问题.为了防止复杂的问题,我会为我的问题编写一个示例代码.现在这是我的问题.

class sample1
{
 public:
 //getter,setter,constructor and destructor functions
 private:
 string label; 

}

class sample2 // in sample2.h #include "sample1" is exist.
{
 public:
  //getter setter constructors and destructors.
  void addSample1(string label);
 private:
  vector<sample1*> sample1's;
}

现在,正如您所看到的,我想用sample1指针填充sample2类中的向量.我尝试使用以下代码执行此操作,但是,显然vector只能存储一个指针,因为在exSample1函数的exacu之后,指针丢失.这是我的代码不起作用.

void addSample1(string label)
{       
        sample1  samp1(label);
    sample1 * n_pointer=new samp1(label);
    n_pointer=&samp1;
    sample1's.push_back(n_pointer);
}

有没有人可以帮我解决问题？提前致谢

Answer 1

你addSample应该只是:

void addSample1(string label)
{       
    sample1s.push_back(new sample1(label));
}

并且一旦完成它们就必须小心并删除这些指针,或者将智能指针存储在向量中.

你在做什么addSample真的很糟糕.

void addSample1(string label)
{       
    // creates a local sample1 object on the stack
    sample1  samp1(label);
    //creates a sample1 object on heap
    sample1 * n_pointer = new sample1(label);
    // overwrites the sample1 pointer with the address of the local object
    // this will leak memory as you have lost the pointer to the dynamically allocated object.
    n_pointer=&samp1;
    //pushes the pointer that points to the local object into the vector
    sample1s.push_back(n_pointer);

   // here the local object is destroyed so now the pointer in the vector 
   // points to deallocated space, accessing it will result in undefined behaviour
}