考虑以下代码:
#include<iostream>
#include<vector>
class A
{
public:
A(int n = 0) : m_n(n) {}
public:
virtual int value() const {return m_n;}
virtual ~A() {}
protected:
int m_n;
};
class B : public A
{
public:
B(int n = 0) : A(n){}
public:
virtual int value() const {return m_n + 1;}
};
int main(char* args[])
{
const A a(1);
const B b(3);
const A *x[2] = {&a, &b};
typedef std::vector<A> V;
V y;
y.push_back(a);
y.push_back(b);
V::const_iterator i = y.begin();
std::cout << x[0]->value() << x[1]->value()
<< i->value() << (i+1)->value() << std::endl;
getchar();
return 0;
}
为什么打印出来1413
,而不是1414
?value()
即使像(i+1)->value();
.