CS253 HW6: Operators!

Description

For this assignment, you will improve your Ratio class, replacing clumsy methods such as .add() with operators.

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 0.75L.
Ratio + Ratio
Ratio - Ratio
Ratio * Ratio
Ratio / Ratio: Add/subtract/multiply/divide the two ratios, yielding another Ratio, returned by value. Do not modify either operand. If division results in a divisor of zero, throw a runtime_error with an appropriate string. Either operand can also be short, int, or long. For example, for a Ratio r, r+3 and 435L/r are valid.
Ratio += Ratio
Ratio -= Ratio
Ratio *= Ratio
Ratio /= Ratio: Combine the two operands with the corresponding arithmetic operation, and replace the left-hand side with the resulting value. Do not modify the right-hand operand. The right-hand operand can also be short, int, or long.
Ratio == Ratio
Ratio != Ratio
Ratio < Ratio
Ratio <= Ratio
Ratio > Ratio
Ratio >= Ratio: Compare two ratios, return true if the condition is true. Ether operand can also be any of short, int, long, float, double or long double.

Non-methods:

ostream << Ratio: Write the numerator, a slash, and the denominator to the ostream. Nothing else—no whitespace.
istream >> Ratio: Read a long numerator, a slash, and a long 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, operands, 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

Every operation must result in a normalized Ratio:

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.

Hints

“OMG! int, short, long double! There are totally too many types! I have to write like nine thousand methods‼” Don’t panic. You don’t have to write methods for all of those. The various arithmetic types naturally promote, as needed. For example, if you write a method that takes a double, it will also take a float.

Debugging

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

    export STACK_FRAME_LINK_OVERRIDE=ffff-ad921d60486366258809553a3db49a4a

Libraries

libhw6.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 libhw6.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 libhw6.a. Particularly, do not put main() in Ratio.h or Ratio.cc. You will also have to create Ratio.h, and put it into hw6.tar. We will test your program by doing something like this:

    mkdir a-new-directory
    cd the-new-directory
    tar -x < /some/where/else/hw6.tar
    cmake . && make
    cp /some/other/place/test-program.cc .@@
    g++ -Wall test-program.cc libhw6.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(hw6 Ratio.cc)
add_executable(test test.cc)
target_link_libraries(test hw6)

# Create a tar file every time:
add_custom_target(hw6.tar ALL COMMAND tar cf hw6.tar Ratio.cc Ratio.h test.cc CMakeLists.txt)
% cat test.cc
#include "Ratio.h"
#include <cassert>
#include <sstream>
#include <iostream>
#include <stdexcept>

using std::cout;
using std::cerr;
using std::istringstream;
using std::runtime_error;

int main() {
    Ratio half(-100,-200), third(half);
    const Ratio five(10/2);
    third.numerator(24);            // now 24/2 ⇒ 12/1
    third.denominator(72);          // now 12/72 ⇒ 1/6
    third *= 2;                     // now 2/6 ⇒ 1/3
    assert(0.3333333333 < third && third < 0.3333333334);
    assert(0.3333333333 < third.ratio() && third.ratio() < 0.3333333334);
    assert(half == half);
    assert(0.5 == half);
    assert(five == 5);
    assert(6 != five);
    assert(half > third);
    assert(half >= third);
    assert(third < half);
    assert(third <= half);
    assert(third != half);
    assert(third + half == Ratio(50,60));
    assert(1/(third * half) == 6.0);
    Ratio a(1), b(2), c(3), d(4);
    a = b = c = d = half;
    assert(a == 0.5);
    assert(0+1/b+0 == 2);
    b /= d;
    assert(b == 1);
    assert(d == half);

    istringstream in(" 1/7\n \n123 / 456 4q5");    // 123/456 ⇒ 41/152
    if (!(in >> a >> b))
        cerr << "read failure\n";
    assert(a.numerator() == 1);
    assert(a.denominator() == 7);
    assert(b.denominator() == 152);
    assert(b.numerator() == 41);
    if (in >> c)
        cerr << "unexpected success\n";
    assert(1 == 2*c);           // must contain old value

    bool caught = false;
    try {
        Ratio bad(1, 0);
    }
    catch (const runtime_error &err) {
        caught = true;
    }
    assert(caught);

    cout << "Hooray!\n";
    return 0;
}
% cmake .
… cmake output appears here …
% make
… make output appears here …
% ./test
Hooray!

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.
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(), execv(), …
You may not use C-style I/O facilities such as printf(), scanf(), fopen(), getchar(), getc(), etc.
- 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.
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: hw6.tar
It must contain:
- source files (*.cc), including Ratio.cc
- header files (*.h), including Ratio.h
- CMakeLists.txt, which will create the library file libhw6.a.
These commands must produce the library libhw6.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 HW6 hw6.tar

How to receive negative points:

Turn in someone else’s work.

CS253: Software Development with C++

Spring 2020

HW 6

CS253 HW6: Operators!

Description

Methods

Some methods are forbidden:

`Ratio` must have the following public methods:

Non-methods:

Normalization

Errors

Hints

Debugging

Libraries

Testing

Sample Run

Hints

Requirements

Tar file

How to submit your work:

How to receive negative points:

CS253 HW6: Operators!

Description

Methods

Some methods are forbidden:

Ratio must have the following public methods:

Non-methods:

Normalization

Errors

Hints

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: