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std::stack::push(3)	       C++ Standard Libary	     std::stack::push(3)

NAME
     std::stack::push - std::stack::push

Synopsis
	void push( const value_type& value );
	void push( value_type&& value );       (since C++11)

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

	1) Effectively calls c.push_back(value).
	2) Effectively calls c.push_back(std::move(value)).

Parameters
	value - the value of the element to push

Return value
	(none)

Complexity
	Equal to the complexity of Container::push_back.

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

     // Run this code

      #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';
      }

Output:
      Hi, cppreference!

See also
	emplace constructs element in-place at the top
	(C++11) (public member function)
	pop	removes the top element
		(public member function)

http://cppreference.com 	   2024.06.10		     std::stack::push(3)
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