107 lines
2.9 KiB
C++
107 lines
2.9 KiB
C++
/**************************************************************************
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*
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* calc.cpp - RPN Calculator -- Illustration of the use of stacks.
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*
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* $Id: calc.cpp 550991 2007-06-26 23:58:07Z sebor $
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*
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***************************************************************************
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed
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* with this work for additional information regarding copyright
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* ownership. The ASF licenses this file to you under the Apache
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* License, Version 2.0 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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* implied. See the License for the specific language governing
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* permissions and limitations under the License.
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*
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* Copyright 1994-2006 Rogue Wave Software.
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*
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**************************************************************************/
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#include <vector>
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#include <stack>
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#include <iostream>
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#include <examples.h>
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// Simulate the behavior of a simple integer calculator.
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struct Calculator
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{
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int currentMemory () const {
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return data_.top ();
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}
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void pushOperand (int value) {
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data_.push (value);
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}
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void doOperator (char);
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private:
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std::stack<int, std::vector<int, std::allocator<int> > > data_;
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};
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void Calculator::doOperator (char theOp)
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{
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int tmp = data_.top ();
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data_.pop ();
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switch (theOp) {
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case '+': tmp = data_.top () + tmp; break;
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case '-': tmp = data_.top () - tmp; break;
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case '*': tmp = data_.top () * tmp; break;
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case '/': tmp = data_.top () / tmp; break;
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case '%': tmp = data_.top () % tmp; break;
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}
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data_.pop ();
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data_.push (tmp);
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}
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int main ()
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{
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std::cout << "Calculator example program, from Chapter 8\n"
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<< "Enter a legal RPN expression, end with p q (print and quit)"
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<< std::endl;
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Calculator calc;
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for (char c; std::cin >> c; ) {
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int intval;
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switch (c) {
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case '0': case '1': case '2': case '3': case '4':
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case '5': case '6': case '7': case '8': case '9':
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std::cin.putback (c);
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std::cin >> intval;
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calc.pushOperand (intval);
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break;
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case '+': case '-': case '*': case '/': case '%':
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calc.doOperator (c);
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break;
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case 'p':
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std::cout << calc.currentMemory () << std::endl;
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break;
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case 'q':
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std::cout << "End calculator program" << std::endl;
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return 0; // quit program
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}
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}
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return 0;
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}
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