Class SeqStack

base_code/template.cpp:36–119

/* 顺序栈模板 */
template<typename T>
class SeqStack
{
public:
    // 构造和析构函数名不用加 <T>，其它出现模板的地方都加上类型参数列表
    SeqStack(int size = 10) 
     : _pstack(new T[size])
    , _top(0)
    , _size(size)
    {}

    ~SeqStack() {
        delete []_pstack;
        _pstack = nullptr;
    }

    SeqStack(const SeqStack<T> &stack)
        : _top(stack._top)
        , _size(stack._size)
    {
        _pstack = new T[_size];
        for (int i = 0; i < _top; ++ i) {
            _pstack[i] = stack._pstack[i];
        }
    }

    SeqStack<T>& operator=(const SeqStack<T> &stack)
    {
        if (this == &stack) return *this;

        delete []_pstack;

        _top = stack._top;
        _size = stack._size;
        _pstack = new T[_size];
        // 不用使用 memcpy 进行浅拷贝
        for (int i = 0; i < _top; ++ i) 
        {
            _pstack[i] = stack._pstack[i];
        }
        return *this;
    }

    void push(const T &val)  // 入栈操作
    {
        if (full()) expand();
        _pstack[_top++] = val;
    }

    void pop() 
    {
        if (empty()) return;
        --_top;
    }

    T top() const
    {
        if (empty()) {
            throw "stack is empty!"; // 抛异常也代表函数逻辑结束