std::stack<T,Container>::push
来自 cppreference.com
void push( const value_type& value ); |
||
void push( value_type&& value ); |
(自 C++11 起) | |
将给定的元素 value 推入栈顶。
1) 实际上调用 c.push_back(value).
2) 实际上调用 c.push_back(std::move(value)).
内容 |
[编辑] 参数
value | - | 要推入的元素的值 |
[编辑] 返回值
(无)
[编辑] 复杂度
等于 Container::push_back 的复杂度。
[编辑] 示例
该程序实现了 BrainHack DSL,当使用 std::stack 是处理配对括号的惯用方式时。
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; unsigned program_pos_{0}; std::array<std::uint8_t, 32768> data_; int data_pos_{0}; void collect_brackets_positions(const std::string_view program) { std::stack<unsigned> brackets_stack; for (auto pos{0U}; pos != program.length(); ++pos) { const char c{program[pos]}; if ('[' == 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 || pos >= static_cast<int>(data_.size())) throw std::out_of_range{"data pointer out of bound"}; } public: BrainHackInterpreter(const std::string_view program) { collect_brackets_positions(program); data_.fill(0); for (; program_pos_ < program.length(); ++program_pos_) switch (program[program_pos_]) { case '<': check_data_pos(--data_pos_); break; case '>': check_data_pos(++data_pos_); break; case '-': --data_[data_pos_]; break; case '+': ++data_[data_pos_]; break; case '.': std::cout << data_[data_pos_]; break; case ',': std::cin >> data_[data_pos_]; break; case '[': if (data_[data_pos_] == 0) program_pos_ = open_brackets[program_pos_]; break; case ']': if (data_[data_pos_] != 0) program_pos_ = close_brackets[program_pos_]; break; } } }; int main() { BrainHackInterpreter { "++++++++[>++>>++>++++>++++<<<<<-]>[<+++>>+++<-]>[<+" "+>>>+<<-]<[>+>+<<-]>>>--------.<<+++++++++.<<----.>" ">>>>.<<<------.>..++.<++.+.-.>.<.>----.<--.++.>>>+." }; std::cout << '\n'; }
输出
Hi, cppreference!
[编辑] 另请参见
(C++11) |
在栈顶就地构造元素 (公共成员函数) |
移除栈顶元素 (公共成员函数) |