Stack<int>

#include <iostream>
using namespace std;
class Stack {
public:
    Stack(size_t buffer = 100)
        : buffer_(buffer), stack_(new int [buffer_]), index_(0) {
    }
    Stack(const initializer_list<int> ilst)
        : buffer_(ilst.size()), stack_(new int[buffer_]), index_(0) {
        for (auto value : ilst) push(value);
    }
    Stack(const Stack& stack)
        : buffer_(stack.capacity()), stack_(new int[buffer_]), index_(stack.index_) {
        for (auto i = 0U; i < index_; ++i) stack_[i] = stack.stack_[i];
    }
    Stack(Stack&& stack)
        : buffer_(stack.capacity()), stack_(move(stack.stack_)), index_(0) {
    }
    ~Stack() {
        if (stack_ != nullptr) {
            delete[] stack_;
            stack_ = nullptr;
            buffer_ = index_ = 0;
        }
    }
    Stack operator=(const Stack& stack) {
        if (this != &stack) {
            buffer_ = stack.buffer_;
            index_ = stack.index_;
            for (auto i = 0U; i < index_; ++i) stack_[i] = stack.stack_[i];
        }
        return *this;
    }
    Stack operator=(Stack&& stack) {
        if (this != &stack) {
            buffer_ = stack.buffer_;
            index_ = stack.index_;
            stack_ = move(stack.stack_);
        }
        return *this;
    }
    void push(int value) {
        if (index_ == buffer_) {
            auto tmp = *this;
            delete [] stack_;
            buffer_ *= 2;
            stack_ = new int[buffer_];
            for (auto i = 0U; i < index_; ++i) stack_[i] = tmp.stack_[i];
        }
        stack_[index_] = value;
        ++index_;
    }
    void push(const initializer_list<int> ilst) {
        for (auto value : ilst) push(value);
    }
    int& top() {
        return stack_[index_ - 1];
    }
    void pop() {
        --index_;
    }
    bool empty()const {
        return 0 == index_;
    }
     size_t size()const {
        return index_;
    }
    size_t capacity()const {
        return buffer_;
    }
private:
    size_t buffer_;
    int* stack_;
    size_t index_;
};
void show(Stack& a) {
    cout << "top: ";
    if (!a.empty()) cout << a.top() << '\n';
    else puts("empty");
    cout
        << "size: " << a.size() << '\n'
        << "capacity: " << a.capacity() << '\n'
        << "--------------\n";
}
int main() {
    Stack a;
    for (auto i = 1; i <= 150; ++i) a.push(i);
    show(a);
    for (auto i = 0; i < 25; ++i) if (!a.empty()) a.pop();
    show(a);
    Stack b = a;
    show(b);
    b.top() = 777;
    show(b);
    a = b;
    show(a);
    Stack c({ 1, 3, 5, 7, 9 });
    show(c);
    c.push({ 2, 4, 6, 8 });
    show(c);
    Stack d(c);
    show(d);
    Stack e(Stack({ 10, 11, 12, 13, 14, 15 }));
    show(e);
    while (!a.empty()) a.pop();
    show(a);
    cout.put('\n');
    system("pause");
}