std::stack<T,Container>::push - cppreference.com (original) (raw)

Pushes the given element value to the top of the stack.

1. Equivalent to: c.push_back(value).

2. Equivalent to: c.push_back(std::move(value)).

[edit] Parameters

[edit] Return value

(none)

[edit] Complexity

Equal to the complexity of Container::push_back.

[edit] Example

This program implements the BrainHack DSL, when the use of std::stack is an idiomatic way to process paired brackets.

#include #include #include #include #include #include #include   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 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(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'; }

Output:

[edit] See also

| | constructs element in-place at the top (public member function) [edit] | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | removes the top element (public member function) [edit] |