Q
class Car
{
public:
int speed;
};
int main()
{
int Car::*pSpeed = &Car::speed;
return 0;
}
为什么这个指针要指向一个非静态类成员？
A
这其实是一个 pointer to member
#include <iostream>
class bowl {
public:
int apples;
int oranges;
};
int count_fruit(bowl * begin, bowl * end, int bowl::*fruit)
{
int count = 0;
for (bowl * iterator = begin; iterator != end; ++ iterator)
count += iterator->*fruit;
return count;
}
int main()
{
bowl bowls[2] = {
{ 1, 2 },
{ 3, 5 }
};
std::cout << "I have " << count_fruit(bowls, bowls + 2, & bowl::apples) << " apples\n";
std::cout << "I have " << count_fruit(bowls, bowls + 2, & bowl::oranges) << " oranges\n";
return 0;
}
count_fruit 的第三个参数，省去了单独编写 count_apples 和 count_oranges 函数的麻烦。
