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extern/stdcxx/4.2.1/examples/tutorial/calc.cpp

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