C++ vector erase method delete my object - c++

Question

I first get an object A from the vector, then I call the erase method to destroy that object in my vector because I don't need it anymore. However, from the debugger, I found that the object A I got before calling erase method is also destroyed. I don't understand that because I thought that what I got is a copy of that object and erase method should have nothing to do with my object A.
Code
Class Unit
Header file
#ifndef UNIT_H
#define UNIT_H
#include <iostream>
class Unit
{
protected:
int id;
public:
Unit::Unit(int num = -1);
virtual ~Unit() = default;
virtual int getID();
};
#endif
CPP file
#include "Unit.h"
Unit::Unit(int num)
{
id = num;
}
int Unit::getID()
{
return id;
}
Class Box
Header file
#ifndef BOX_H
#define BOX_H
#include <string>
#include <iostream>
#include "Unit.h"
class Box : public Unit
{
private:
std::string* type;
int* val;
public:
Box::Box();
~Box();
int getVal();
std::string getName();
int getID() override;
};
#endif
CPP file
#include <time.h>
#include "Box.h"
Box::Box() : Unit(5)
{
int tmp = rand() % 3;
if (tmp == 0)
{
type = new std::string("hp"); // health cur
val = new int(rand() % 10 + 1);
}
else if (tmp == 1)
{
type = new std::string("exp"); // skill level or health max
val = new int(rand() % 5 + 1);
}
else
{
type = new std::string("punish"); // minus health cur
val = new int(-1);
}
}
Box::~Box()
{
delete type;
delete val;
}
int Box::getVal()
{
return *val;
}
std::string Box::getName()
{
return *type;
}
int Box::getID()
{
return id;
}
main file
using namespace std;
int main()
{
Box test;
std::vector<Box> bag;
bag.push_back(test);
Box tmp = bag[0];
bag.erase(bag.begin() + 0);
cout << tmp.getVal();
system("pause");
return 0;
}
Below is the screenshot from the debugger and because I don't have 10 reputations, I can't display it directly.
before
after
As you can see, the "type" and "val" data member of class Box is modified.

Answer 1

Check out this page about the return type from the index call
http://en.cppreference.com/w/cpp/container/vector/operator_at
I believe that you may have a reference, not a different object.