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std::stack<T,Container>:: push

From cppreference.net

C++
Containers library
std::stack
void push ( const value_type & value ) ;
(1)
void push ( value_type && value ) ;
(2) (自 C++11 起)

将给定元素 value 压入栈顶。

1) 等价于： c. push_back ( value ) 。
2) 等价于： c. push_back ( std :: move ( value ) ) 。

目录

参数

value - 要压入的元素值

返回值

(无)

复杂度

等于 Container :: push_back 的复杂度。

示例

本程序实现了 BrainHack DSL ，其中使用 std::stack 是处理配对括号的惯用方法。

运行此代码 
#include <array>
#include <cstdint>
#include <iostream>
#include <map>
#include <stack>
#include <stdexcept>
#include <string_view>
class BrainHackInterpreter
{
    std::map<unsigned, unsigned> open_brackets, close_brackets;
    std::array<std::uint8_t, 32768> data_{0};
    unsigned program_{0};
    int pos_{0};
    void collect_brackets(const std::string_view program)
    {
        std::stack<unsigned> brackets_stack;
        for (auto pos{0U}; pos != program.length(); ++pos)
        {
            if (const char c{program[pos]}; '[' == c)
                brackets_stack.push(pos);
            else if (']' == c)
            {
                if (brackets_stack.empty())
                    throw std::runtime_error("Brackets [] do not match!");
                else
                {
                    open_brackets[brackets_stack.top()] = pos;
                    close_brackets[pos] = brackets_stack.top();
                    brackets_stack.pop();
                }
            }
        }
        if (!brackets_stack.empty())
            throw std::runtime_error("Brackets [] do not match!");
    }
    void check_data_pos(int pos)
    {
        if (pos < 0 or static_cast<int>(data_.size()) <= pos)
            throw std::out_of_range{"Data pointer out of bound!"};
    }
public:
    BrainHackInterpreter(const std::string_view program)
    {
        for (collect_brackets(program); program_ < program.length(); ++program_)
            switch (program[program_])
            {
                case '<':
                    check_data_pos(--pos_);
                    break;
                case '>':
                    check_data_pos(++pos_);
                    break;
                case '-':
                    --data_[pos_];
                    break;
                case '+':
                    ++data_[pos_];
                    break;
                case '.':
                    std::cout << data_[pos_];
                    break;
                case ',':
                    std::cin >> data_[pos_];
                    break;
                case '[':
                    if (data_[pos_] == 0)
                        program_ = open_brackets[program_];
                    break;
                case ']':
                    if (data_[pos_] != 0)
                        program_ = close_brackets[program_];
                    break;
            }
    }
};
int main()
{
    BrainHackInterpreter
    {
        "++++++++[>++>>++>++++>++++<<<<<-]>[<+++>>+++<-]>[<+"
        "+>>>+<<-]<[>+>+<<-]>>>--------.<<+++++++++.<<----.>"
        ">>>>.<<<------.>..++.<++.+.-.>.<.>----.<--.++.>>>+."
    };
    std::cout << '\n';
}

输出： 

Hi, cppreference!

参见

(C++11)
在栈顶就地构造元素
(公开成员函数)
移除栈顶元素
(公开成员函数)