c++ 类模板对象怎样分类实例化?

发布网友发布时间：2023-07-20 15:25

共4个回答

热心网友时间：2024-12-04 11:29

#include <iostream>

using namespace std;

class StackBase
{
public:
    virtual ~StackBase() {}
    virtual void push() = 0;
    virtual void pop() = 0;
};

class StackWrapper : public StackBase
{
    StackBase* impl_;
public:
    ~StackWrapper() { if (impl_) delete impl_; }
    StackWrapper() : impl_(0) {}
    void push();
    void pop()
    {
        if (impl_)
            impl_->pop();
        else
            cout << "the stack is empty";
    }
};

template <class numtype>
class Stack : public StackBase
{
    friend class StackWrapper;
    enum { stack_max = 100 };
    numtype stack[stack_max];

    void pushNum(numtype x)
    {
        stack[++n] = x;
    }
public:
    Stack()
    {
        n = 0;
    }
    void push()
    {
        if (n == stack_max - 1)
        {
            cout << "failed beacuse the stack is full";
            return;
        }
        cout << "input the number you wanna push in:";
        cin >> stack[++n];
    }
    void pop()
    {
        if (n <= 0)
        {
            cout << "the stack is empty";
            return;
        }
        cout << "the digital you want:";
        cout << stack[n--] << endl;
    }
private:
    int n;
};

void StackWrapper::push()
{
    if (impl_)
        impl_->push();
    else
    {
        int x;
        double y, t;
        cout << "input the number you wanna push in:";
        cin >> y;
        x = y;
        t = y - x;
        if (t < 0) t = -t;
        if (t < 1e-8) //int
        {
            Stack<int>* r = new Stack<int>();
            cout << "Stack<int> created." << endl;
            impl_ = r;
            r->pushNum(x);
        }
        else
        {
            Stack<double>* r = new Stack<double>();
            cout << "Stack<double> created." << endl;
            impl_ = r;
            r->pushNum(y);
        }
    }
}

int main()
{
    StackWrapper s;
    s.push();
    s.push();
    s.push();
    s.pop();
    s.pop();
    return 0;
}

你想以第一个输入的数字来决定吗……如果第一个是int第二个是double会死喔

勉强写了一下，看到问题第一个想到的是这样做

热心网友时间：2024-12-04 11:29

用swtich也行

热心网友时间：2024-12-04 11:30

楼主能说得再具体点吗？

热心网友时间：2024-12-04 11:31

怎么选择？条件是什么？