SimpleCalc -- simple calculator using 1.5 java.util.Scanner
/*
* Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
* All rights reserved. Software written by Ian F. Darwin and others.
* $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
* cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
* pioneering role in inventing and promulgating (and standardizing) the Java
* language and environment is gratefully acknowledged.
*
* The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
* inventing predecessor languages C and C++ is also gratefully acknowledged.
*/
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.io.Reader;
import java.util.Scanner;
import java.util.Stack;
/**
* SimpleCalc -- simple calculator using 1.5 java.util.Scanner
* @version $Id: SimpleCalcScanner.java,v 1.3 2004/03/10 18:01:35 ian Exp $
*/
public class SimpleCalcScanner {
/** The Scanner */
protected Scanner scan;
/** The output */
protected PrintWriter out = new PrintWriter(System.out);
/** The variable name (not used in this version) */
protected String variable;
/** The operand stack */
protected Stack s = new Stack();
/* Driver - main program */
public static void main(String[] av) throws IOException {
if (av.length == 0)
new SimpleCalcScanner(
new InputStreamReader(System.in)).doCalc();
else
for (int i=0; i<av.length; i++)
new SimpleCalcScanner(av[i]).doCalc();
}
/** Construct a SimpleCalcScanner by name */
public SimpleCalcScanner(String fileName) throws IOException {
this(new FileReader(fileName));
}
/** Construct a SimpleCalcScanner from an open Reader */
public SimpleCalcScanner(Reader rdr) throws IOException {
scan = new Scanner(rdr);
// Control the input character set:
scan.slashSlashComments(true); // treat "//" as comments
scan.ordinaryChar('-'); // used for subtraction
scan.ordinaryChar('/'); // used for division
}
/** Construct a SimpleCalcScanner from a Reader and a PrintWriter */
public SimpleCalcScanner(Reader rdr, PrintWriter pw) throws IOException {
this(rdr);
setWriter(pw);
}
/** Change the output to go to a new PrintWriter */
public void setWriter(PrintWriter pw) {
out = pw;
}
protected void doCalc() throws IOException {
int iType;
double tmp;
while (scan.hasNext()) {
if (scan.hasNextDouble()) {
push(scan.nextDouble());
} else {
String token = scan.next().toString();
if (token.equals("+")) {
// Found + operator, perform it immediately.
push(pop() + pop());
} else if (token.equals("-")) {
// Found - operator, perform it (order matters).
tmp = pop();
push(pop() - tmp);
} else if (token.equals("*")) {
// Multiply is commutative
push(pop() * pop());
} else if (token.equals("/")) {
// Handle division carefully: order matters!
tmp = pop();
push(pop() / tmp);
} else if (token.equals("=")) {
out.println(peek());
} else {
out.println("What's this? " + token);
}
}
}
}
void push(double val) {
s.push(new Double(val));
}
double pop() {
return ((Double)s.pop()).doubleValue();
}
double peek() {
return ((Double)s.peek()).doubleValue();
}
void clearStack() {
s.removeAllElements();
}
}
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