CS253 HW4: Time to get classy!

Description

For this assignment, you will write a standalone class called Ratio, which will represent a fraction, e.g., 2/3 or −6/5. Specifically, you will provide Ratio.h, which will contain the interface of that class, and the library libhw4.a, which will contain the implementation of that class.

Methods

Some methods are forbidden:

no default ctor: The default (no-argument) ctor for Ratio must fail to compile. This is not a run-time error; it’s a compile-time error.
no floating-point ctors: Ratio(float), Ratio(double), and Ratio(long double) must all fail to compile.

`Ratio` must have the following public methods:

Ratio(long numerator, long denominator): Create a ratio representing the fraction numerator/denominator. If the denominator is not given, assume a denominator of one. If the denominator is zero, throw a runtime_error with an appropriate string.
Ratio(int numerator, int denominator): Same as above, but using ints rather than longs.
Copy constructor: Copy all information from another object of the same class.
Assignment operator: Copy all information from another object of the same class, replacing any previous information.
Destructor: Destroy.
.numerator(): Return the numerator as a long.
.numerator(long): Set the numerator.
.denominator(): Return the denominator as a long.
.denominator(long): Set the denominator. If the denominator is zero, throw a runtime_error with an appropriate string, and leave the object unchanged.
.ratio(): Return a long double representing the fraction. For example, Ratio(3,4).ratio() would return a long double with the value 0.75.
.add(Ratio, …): Add all the arguments to the current Ratio, resulting in yet another Ratio, returned by value. This method will not modify the current object, or any arguments. It is possible for this method to have one to eight Ratio arguments.
.subtract(Ratio): Subtract the argument from the current Ratio, resulting in a third Ratio, returned by value. This method will not modify the current object, or the argument.
.multiply(Ratio): Multiply the argument by the current Ratio, resulting in a third Ratio, returned by value. This method will not modify the current object, or the argument.
.divide(Ratio): Divide the current Ratio by the argument, resulting in a third Ratio, returned by value. This method will not modify the current object, or the argument. If this results in a divisor of zero, throw a runtime_error with an appropriate string.
.compare(Ratio): Compare the current object to another Ratio. If the current object is smaller, return an int less than zero. If the current object is larger, return an int greater than zero. If they’re equal, return zero.
.compare(long double): Compare the .ratio() of the current object to a long double. If the current object is smaller, return an int less than zero. If the current object is larger, return an int greater than zero. If they’re equal, return zero.

Non-methods:

ostream << Ratio: Write the numerator, a slash, and the denominator to the ostream. Nothing else—no whitespace.
istream >> Ratio: Read a long int numerator, a slash, and a long int denominator from the istream, skipping optional whitespace before each one. If an error occurs, set the state of the istream to failure, and leave the Ratio object unchanged. A zero divisor can either cause istream failure, throw a runtime_error, or both.

Const-correctness, for arguments, methods, and operators, is your job. For example, it must be possible to call .ratio() on a const Ratio, or to add a two const Ratio objects together.

You may define other methods or data, public or private, as you see fit. You may define other classes, as you see fit. However, to use the Ratio class, the user need only #include "Ratio.h", not any other header files.

Normalization

A Ratio must be normalized :

It must be reduced to lowest terms (66660/88880 becomes 3/4).
The denominator must be positive (−4/−3 becomes 4/3, and 9/−100 becomes −9/100).
If the numerator is zero, a non-zero denominator must be one (0/177777 becomes 0/1).

Errors

All errors are indicated by throwing a runtime_error with an explanatory message. The exact string thrown is up to you, but should be descriptive and understandable by the TA.
No Ratio method should call exit(), or produce any output.
Numeric overflow (e.g., by multiplying two very large values) results in undefined behavior.

Debugging

If you encounter “STACK FRAME LINK OVERFLOW”, then try this:

    export STACK_FRAME_LINK_OVERRIDE=ffff-ad921d60486366258809553a3db49a4a

Libraries

libhw4.a is a library file. It contains a number of *.o (object) files. It must contain Ratio.o, but it may also contain whatever other *.o files you need. The CMakeLists.txt shown creates libhw4.a. It does not contain main().

Testing

You will have to write a main() function to test your code. Put it in a separate file, and do not make it part of libhw4.a. Particularly, do not put main() in Ratio.h or Ratio.cc. You will also have to create Ratio.h, and put it into hw4.tar. We will test your program by doing something like this:

    mkdir a-new-directory
    cd the-new-directory
    tar -x </some/where/else/hw4.tar
    cmake . && make
    cp /some/other/place/test-program.cc .
    g++ -Wall test-program.cc libhw4.a
    ./a.out

We will supply a main program to do the testing that we want. You should do something similar.

Sample Run

Here is a sample run, where % is my shell prompt:

% cat CMakeLists.txt
cmake_minimum_required(VERSION 3.14)
project(Homework)

# Using -Wall is required:
add_compile_options(-Wall)

# These compile flags are highly recommended, but not required:
add_compile_options(-Wextra -Wpedantic)

# Optional super-strict mode:
add_compile_options(-fmessage-length=80 -fno-diagnostics-show-option)
add_compile_options(-fstack-protector-all -g -O3 -std=c++14 -Walloc-zero)
add_compile_options(-Walloca -Wctor-dtor-privacy -Wduplicated-cond)
add_compile_options(-Wduplicated-branches -Werror -Wfatal-errors -Winit-self)
add_compile_options(-Wlogical-op -Wold-style-cast -Wshadow)
add_compile_options(-Wunused-const-variable=1 -Wzero-as-null-pointer-constant)

# add_compile_options must be BEFORE add_executable or add_library.

add_library(hw4 Ratio.cc)
add_executable(test test.cc)
target_link_libraries(test hw4)

# Create a tar file every time:
add_custom_target(hw4.tar ALL COMMAND tar cf hw4.tar Ratio.cc Ratio.h test.cc CMakeLists.txt)
% cat test.cc
#include "Ratio.h"
#include <cassert>
#include <fstream>
#include <iostream>
#include <stdexcept>

using std::cerr;
using std::cout;
using std::ifstream;
using std::runtime_error;

int main() {
    Ratio f12(-2,-4), f34(3L,4L), seven_eights = Ratio(7).divide(Ratio(8));
    const Ratio f78(seven_eights), one(f34.divide(f34));
    assert(f12.numerator() == 1);
    assert(f12.denominator() == 2);
    assert(f12.ratio() == 0.5);
    assert(f34.ratio() == 0.75);
    assert(f78.ratio() == 0.875);
    assert(f12.add(f34).multiply(f78).ratio() == 1.09375);
    assert(f12.ratio() == 0.5);
    assert(f34.ratio() == 0.75);
    assert(f78.ratio() == 0.875);
    assert(Ratio(1,5).add(Ratio(1,7)).compare(Ratio(12,35)) == 0);

    assert(f12.compare(f34) < 0);
    assert(f34.compare(f12) > 0);
    assert(f34.compare(Ratio(-66,-88)) == 0);
    assert(f12.add(f34).compare(Ratio(5,4)) == 0);
    assert(f12.add(f34).ratio() == 1.25);
    assert(f12.add(f34).compare(1.25L) == 0);
    assert(f12.add(f34, f78, f12, f34, f78).ratio() == 4.250);
    assert(f34.add(one,one,one,one,one,one,one,one).ratio() == 8.75);

    Ratio r(42, 666);
    r.numerator(0);
    r.numerator(700);
    r.denominator(-3000);
    assert(r.numerator() == -7);
    assert(r.denominator() == 30);

    cout << "Should be |-7/30|: |" << r << "|\n";

    ifstream in("data");
    if (!in) {
        cerr << "Can’t open data\n";
        return 1;
    }
    while (in >> r)
        cout << "»»» " << r << '\n';

    try {
        r.denominator(0);
        cout << "Should not get here.\n";
    }
    catch (const runtime_error &err) {
        cout << "Error detected: "  << err.what() << '\n';
    }

    return 0;
}
% cat data
03/-4           -0/999      

 0100 / +8         
% cmake .
… cmake output appears here …
% make
… make output appears here …
% ./test
Should be |-7/30|: |-7/30|
»»» -3/4
»»» 0/1
»»» 25/2
Error detected: divisor of zero

Hints

Fractions are tricky: ½ + ⅓ ≠ ⅖. Read Wikipedia for a refresher on fractions.
This is an int: 24. This is a long: 68L. This is a float: 1.2F. This is a double: 3.4. This is a long double: 5.6L.
If you use try…catch in your Ratio code, you probably don’t understand exceptions—seek help.
“whitespace” is not just a fancy way of saying “space”. It’s what isspace() says it is.
See https://en.cppreference.com/w/cpp/io/basic_ios/setstate for how to put a stream in a failed state.
The foolish student will put main() in Ratio.cc, and try to remember to remove it before turning in the homework. Good luck with that. Just put it in a separate file.

Requirements

You have permission to copy GCD (Greatest Common Divisor) or LCM (Least Common Multiple) code from a book or the internet. However, you must have a comment before the copied code citing the book (Author, title, page) or URL where you found the code.
Only .add() takes from one to eight arguments, not .subtract(), .multiply(), or .divide().
In case of a failed input operation (>>), the position of the input stream is unspecified.
You may use the CMakeLists.txt shown, or create your own.
Do not put using namespace std; in any header file.
All copies (copy ctor, assignment operator) are “deep”. Do not share data between copies—that’s not making a copy.
You may not use any external programs via system(), fork(), popen(), execl(), execvp(), etc.
You may not use C-style I/O, such as printf(), scanf(), fopen(), and getchar().
- Instead, use C++ facilities such as cout, cerr, and ifstream.
You may not use dynamic memory via new, delete, malloc(), calloc(), realloc(), free(), strdup(), etc.
- It’s ok to implicitly use dynamic memory via containers such as string or vector.
You may not use the istream::eof() method.
No global variables.
For readability, don’t use ASCII int constants (65) instead of char constants ('A') for printable characters.
We will compile your program like this: cmake . && make
- If that generates warnings, you will lose a point.
- If that generates errors, you will lose all points.
There is no automated testing/pre-grading/re-grading.
- Test your code yourself. It’s your job.
- Even if you only change it a little bit.
- Even if all you do is add a comment.

If you have any questions about the requirements, ask. In the real world, your programming tasks will almost always be vague and incompletely specified. Same here.

Tar file

The tar file for this assignment must be called: hw4.tar
It must contain:
- source files (*.cc), including Ratio.cc
- header files (*.h), including Ratio.h
- CMakeLists.txt, which will create the library file libhw4.a.
These commands must produce the library libhw4.a:

    cmake . && make

Your CMakeLists.txt must use at least -Wall when compiling.

How to submit your work:

Use web checkin, or Linux checkin:

    ~cs253/bin/checkin HW4 hw4.tar

How to receive negative points:

Turn in someone else’s work.

CS253: Software Development with C++

Spring 2020

HW 4

CS253 HW4: Time to get classy!

Description

Methods

Some methods are forbidden:

`Ratio` must have the following public methods:

Non-methods:

Normalization

Errors

Debugging

Libraries

Testing

Sample Run

Hints

Requirements

Tar file

How to submit your work:

How to receive negative points:

CS253 HW4: Time to get classy!

Description

Methods

Some methods are forbidden:

Ratio must have the following public methods:

Non-methods:

Normalization

Errors

Debugging

Libraries

Testing

Sample Run

Hints

Requirements

Tar file

How to submit your work:

How to receive negative points:

`Ratio` must have the following public methods: