C++ 栈类实力 代码分析

#include <vector>

class istack{
public:
        istack (int capacity):_stack(capcity),_top(0){}
        bool pop(int &value);
        bool push(int value);

        bool full();
        bool empty();
        bool display();

        int size()
private;
        int _top;
        vector <int> _stack;

}