Homework 1 Problem 1 & 2 Velocity class Solution

Description

Create a C++ class Velocity that represents the velocity of a car. The velocity can only take integer values. It can be positive (describing forward motion) but not larger than 65. If it is negative (reverse motion) it cannot be smaller than -5. Any attempt to set the velocity to a value larger than 65 should result in the velocity being 65. Likewise, any attempt to set the velocity to a value lower than -5 should result in the velocity being -5.

The class Velocity should include a public member function accelerate(int dv) and a private member function set(int v). The accelerate function uses the set function to change the velocity by the amount dv. The argument dv may be positive or negative. The initial velocity after creation of a Velocity object should be zero. See the file Velocity.h for details and other member functions.

The Velocity class is used by a program useVelocity.cpp that is provided. The output of the program useVelocity must reproduce exactly the contents of the file useVelocity.out.

The files Velocity.h and useVelocity.cpp are provided and must not be modified. You must create a file Velocity.cpp containing the implementation of your Velocity class. It must be possible to compile the program useVelocity.cpp using

g++ -Wall -o useVelocity Velocity.cpp useVelocity.cpp

without generating any warning message.

Submission

Create a tar file named hw1p1.tar containing the files useVelocity.cpp Velocity.cpp, Velocity.h, and Makefile. Do not compress the tar file. The files useVelocity.cpp and Velocity.h must be identical to the files provided. The Makefile must contain a target all and a target clean. The target all should appear first and will be used to build the executable useVelocity. The target clean will be used to remove all object files and executables. The Makefile should include the necessary definition to compile C++ files with the –Wall option. Include your name and Student ID in a comment at the top of each file (except useVelocity.cpp and Velocity.h). Submit your project using:

$ handin cs36b hw1 hw1p1.tar
Problem 2: Fraction calculator

Description

Create a simple fraction calculator that can add and subtract any number of fractions and writes the answer as a reduced fraction.

Your program will read input from stdin and write output on stdout.

A fraction is represented as the sequence:

a/b

where a and b are integers and any amount of white space characters ' ' (including none) can separate a from '/' and '/' from b.
Input consists of an expression made of fractions separated by the operators '+' or '-'. The number of fractions in the expression is arbitrary. Each of the following 6 lines is an example of valid input expression:

1/2 + 3/4

1/2-5/7+3/5
355/113

    3 /9- 21 / -7 4/7-5/-8 -2/-3--7 /5

Note that the numerator and/or denominator of a fraction given as input may be negative.

The input will consist of a single expression on a single line terminated by a \n character.

The output should consist of a single, irreducible fraction written as

c/d

where c is a signed integer and d is a positive integer (i.e. the denominator cannot be negative in the output). The numbers c and d should not have any common factors (apart from 1).

Error processing and special cases

You can expect the input to consist of complete expressions, i.e. there will be no incomplete or missing fractions in the input. Fractions with a zero denominator may appear in input, and must cause the following error message to be printed on stdout:

Error: zero denominator

with no other output.

If the answer is an integer, the program should only print that integer and not a fraction
Example:  input= 3/2 + 4/8 , output = 2

Examples of input and corresponding output will be provided in the file homework1.tar. Your output should exactly match the output in the example files (including spaces if any).


Implementation

The main program, called calculator.cpp , is provided. Your project must include a class

Fraction that encapsulates all functions related to the processing of fractions. The >> and <<

operators must be overloaded and used to read and write fractions. The presence of a zero
denominator in input should be handled by throwing an exception of type
invalid_argument defined in <stdexcept>. The class Fraction must be defined in a

source file Fraction.cpp and declared in a header file Fraction.h. The implementation
of the member functions should be defined in the file Fraction.cpp. The class Fraction must
include a constructor Fraction::Fraction(int a, int b). The internal

representation of the fraction should be in reduced form, i.e. using a pair of numbers that have no
common factors. Constructors and other member functions must ensure that the fraction is
always reduced. Use Euclid's algorithm to simplify fractions to reduced form. An example of a C
implementation reduce_fraction.c of this algorithm is provided in the file homework1.tar. Do not

include the file reduce_fraction.c in your submission. The operators '+', '-' and '=' must be

overloaded and defined. Member functions getNum() and getDen() should be implemented,
returning the (reduced) numerator and denominator of the fraction. It should be possible to use
the class Fraction in the program useFraction.cpp which #includes the header

Fraction.h. The program useFraction.cpp is provided in the file homework1.tar. You

should not modify that program.


Submission

Create a tar file named hw1p2.tar containing the files calculator.cpp Fraction.cpp Fraction.h useFraction.cpp and Makefile. Do not compress the tar file. The files calculator.cpp and useFraction.cpp must be identical to the files provided. The Makefile must contain a target calculator , a target useFraction, a target all, and a target clean. The target all should appear first and will be used to build both executables. The target clean will be used to remove all object files and executables. The Makefile should include the necessary definition to compile C++ files with the –Wall option. Include your name and Student ID in a comment at the top of each file (except calculator.cpp and useFraction.cpp). Submit your project using:

$ handin cs36b hw1 hw1p2.tar