DC Calculator Program

Designed by: Ervin Pangilinan

Semester: Spring 2022 (v1.0) March 18, 2022

Course: CSC 245 - Data Stuctures & Algorithms Analysis

Language Used: C++

Objective

The goal of this project is to recreate the dc calculator found in Linux terminals. The client program is designed with an implementation file of a stack class. Input is taken from the keyboard in postfix notation and will continue to do so until the user specifies the end of file with CTRL+D.

Command Line Syntax

./a.out

Features

The base features for modifying the implemented stack are listed below along with their respective commands:

• printing the top value of the stack (p)
• printing the top value value of the stack and popping it (n)
• printing the entire stack (f)
• clearing the entire stack (c)
• duplicating the top value of the stack (d)
• swapping the top two values of the stack (r)

The base math operations are listed below, along with their respective symbols:

NOTE: The operations are done in the following order:

(second-popped value) [operator] (first-popped value)

• addition (+)
• subtraction (-)
• multiplication (*)
• division (/)
• modulus (%)

Additional features are listed below:

• exponentiate (^)
• square root with truncated result (v) *NOTE: This will only pop one value instead of two.
• quotient and remainder (~)
• reading the remainder of a line of input as a comment (#)
• error handling to prevent input of doubles and numbers larger or smaller than the bounds of a standard int

Sample Input

Input is taken from the keyboard going line by line until end of input is reached. An example is listed below:

2 3 +
p
6 - p
4 6 * + p
2 / p
4 % p
2 100 +
3 4 5 f
5d*p
rf2pc
f
<CTRL+D>

This input is taken in postfix notation and exception handling is done for any instances of DataErrors, Stack Overflows, Stack Underflows, DivisionByZero, and OutOfMemory errors.

Sample Output

Output will be shown on-screen depending on the operands and operators that were previously inputted. An example is listed below:

5
-1
23
11
3
5 4 3 102 3
25
5 25 4 3 102 3
2

If an exception is caught, the program will output the following:

dc: [error]

OOP Design

Along with the implementation of a stack class, the following classes are included in the client program:

• iostream
• cstdlib
• cctype
• cmath

Program Outline

The client program can be split into 3 different steps:

• Step 1: Taking input
• Step 2: Parsing integers
• Step 3: Performing commands and operations

Taking Input

The program runs until <CTRL+D> or end of file is met, so the program will continue to process each line of input. To parse through a line of input, the program iterates through the input line and determines what case to follow depending on what each character is. The next 2 steps outline what the program will execute if the character can be treated as an operand or operator.

Parsing Integers

While iterating through the input line, if the program determines that the character is a digit, the program will record the character at that index and will concatenate to a string until a non-operand is met. When a non-operand is found, the program will convert the operand string into an integer and push it onto the stack. For negative numbers, if a '_' is found, the program will first concatenate a '-' onto the operand string then continue as normal for a positive integer.

Possible exceptions that can arise are DataErrors from inputting a double value and OutOfMemory errors from inputting integers that are outside the range of a standard int. When these exceptions occur, the program will not parse the input and instead skips the rest of the line.

Performing Operations & Commands

When a symbol is reached that denotes a operation or command, it will perform the given action based on the symbol and continues to iterate through the input string. This action is applicable to all stack commands and math operations.