后缀运算器（已补全)

#include "mystack.h" #include <iostream> using namespace std; char get_command() { char command; bool waiting = true; cout << "Select command and press <ENTER> : "; while (waiting){ cin >> command; if (command == '?' || command == '=' || command == '+' || command == '-' || command == '*' || command == '/' || command == 'q') waiting = false; else{ cout << "Please enter a valid command:"<< endl << "[?]push to stack [=]print top" << endl << "[+][-][*][/]" << endl << "[q]exit." << endl; } } return command; } bool do_command(char command, Stack &numbers) { double p,q; switch (command){ case '?': cout << "Enter a real number." <<flush; cin >> p; if (numbers.push(p) == overflow) cout << "Waring :stack full,lost numbers" <<endl; break; case '=' : if(numbers.top(p) == underflow) cout << "Stack empty" <<endl; else cout << p <<endl; break; case '+': if (numbers.top(p) == underflow) cout << "stack empty" <<endl; else{ numbers.pop(); if (numbers.top(q) == underflow) cout << "stack has just one entry" <<endl; numbers.push(p); } else{ numbers.pop(); if (numbers.push(p+q) == overfloww) cout << "Warring : stack full,lost result" << endl; } } break; case '-': if (numbers.top(p) == underflow) cout << "stack empty" <<endl; else{ numbers.pop(); if (numbers.top(q) == underflow) cout << "stack has just one entry" <<endl; numbers.push(p); } else{ numbers.pop(); if (numbers.push(p-q) == overfloww) cout << "Warring : stack full,lost result" << endl; } } break; case '*': if (numbers.top(p) == underflow) cout << "stack empty" <<endl; else{ numbers.pop(); if (numbers.top(q) == underflow) cout << "stack has just one entry" <<endl; numbers.push(p); } else{ numbers.pop(); if (numbers.push(p*q) == overfloww) cout << "Warring : stack full,lost result" << endl; } } break; case '/': if (numbers.top(p) == underflow) cout << "stack empty" <<endl; else{ numbers.pop(); if (numbers.top(q) == underflow) cout << "stack has just one entry" <<endl; numbers.push(p); } else{ if (q == 0) cout << "againt / precept!" <<endl; else numbers.pop(); if (numbers.push(p/q) == overfloww) out << "Warring : stack full,lost result" << endl; } } case 'q'; cout << "calculation finished.\n"; return false; } return true; } void main() { Stack numbers; while (do_command(get_command(),stored_numbers)); }