COMP2396B - Assignment 1

Due: 12 Feb, 2019 23:55

Introduction

This assignment tests your basic programming skill in Java and refreshes the programming skills

that you should have learnt in the first programming course.

You are asked to write an infix to postfix convertor. Although program design will not be

evaluated in this assignment, you are encouraged to apply the object-oriented programming

technique that you have learnt, in particular, the principles of abstraction and encapsulation.

You are also required to write JavaDoc for all non-private classes and non-private class

members. Programs without JavaDoc will not be marked.

Requirements

You will be provided a skeleton file, InfixReader.java, which consists of a simple main()

method that controls the basic program flow; and a method that reads a line from input which

is implemented for you. You will need to implement the doConversion() method that read

an infix from input (using the provided readInfix() method), convert that to postfix and

print it out. You also need to implement the evalPostfix() method that will evaluate the

postfix representation of the input arithmetic expression, and then print the result of the

evaluation of the expression on the next line.

To support the infix to postfix conversion and the evaluation of postfix expression, you are

required to implement the class Stack. You are not allowed to use any class provided in the

packages in java.util.* or any other Java classes that provide the implementation of a

stack from the Internet. Please refer to the tutorial for the basic operations of a stack.

Your program should read in an integer arithmetic expression in infix form, and output the same

expression in postfix form. Numbers and operators in the expression are separated by at least

one single space. (NOTE: ALL NUMBERS IN THE EXPRESSIONS ARE INTEGERS)

For example:

Input infix: 12 + 23

Postfix: 12 23 +

Result: 35

Input infix: 34 * 56

Postfix: 34 56 *

Result: 1904

Your program should support the five arithmetic operators, ^, +, -, * and /. The ^ is the

exponential operator and has the highest precedence. The precedence of operators * and / are

higher than that of operators + and -. For example:

Input infix: 1 + 2 * 3

Postfix: 1 2 3 * +

Result: 7

Input infix: 8 – 64 / 4 ^ 2

Postfix: 8 64 4 2 ^ / -

Result: 4

Your program should also support the use of parenthesis. For example:

Input infix: ( 1 + 2 ) * 3

Postfix: 1 2 + 3 *

Result: 9

* Note the spacing before and after the parenthesis.

Your program should support negative values. There is no space between the negative sign and

the number in negative values. For example:

Input infix: 5 + -2 * 2

Postfix: 5 -2 2 * +

Result: 1

Marking

- 60% marks are given to the functionality of your program.

You may add additional classes, instant variables and methods to the class.

You may assume that the input is always a valid, space delimited infix expression.

Your program output must be identical to what is described in this document, with the

exception of the trailing spaces at the end of each line of output.

- 40% marks are given to your JavaDoc. A complete JavaDoc includes documentation of

every classes, member fields and methods that are not private. JavaDoc for the main method

may be omitted.

Submission:

Please submit the following files to Moodle. Late submission is not allowed.

InfixReader.java

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