[Solved] Coding Assignment 2: The PhysVec Class

The PhysVec class is short for Physics Vector. Physics vectors are used to describe things like velocity and acceleration physics. They differ from ordinary vectors because I say so. You will take the class header file I am giving you and you will be creating the class implementation file (.cpp) that makes everything work. You will also create a main file that will be used for testing the class. I am providing you with a sample main file that I used when I was writing the class myself. I will repeat this later for emphasis!

There are several things that I am going to require of you.

Basics:

1. You will write and test your code on the professional level IDE cLion
2. You will submit your results on TRACS. Do NOT put them in a zip file, just post the main, both class files and CMAKE file.
3. You will name the class PhysVec and the main file main. You will use the exact .h file I gave you.
4. Please treat this as if you were doing it on the job and you were going to provide this to your coworkers. If you dont understand what I mean by that, you better get it clarified.
5. I cannot and will not tell you exactly how to do this assignment. You are professionals in training; you need to deal with some ambiguity and figure things out. Thats real life. You can always ask for clarification.
6. I will describe for each item in the .h file how I would attack it. Combined with the lecture material and googling and the reading, you should be able to do this assignment reasonably easily. If I have left something out, email me to ask and I can then provide an answer to everyone if appropriate.
7. You will need to follow the basic coding standards we will talk about in class. Do NOT use using namespace std, use my naming conventions, good variable names, good comments, ect.
8. You will test your code with a variety of inputs that reflect limits and combinations and bad data reaction.
9. I will likely think of more requirements, possibly after you have already started so dont make code thats hard to update and dont get pissy if I do since this happens all the time to coders in the process of a real job.

PhysVec Class Header File PhysVec.h (see file)

1. PhysVec(); This is the default constructor taking no arguments. It just creates a PhysVec instance. Simplest possible implementation. // Constructor that takes a vector to be turned into a PhysVec2. PhysVec(const std::vector<int> & input_vec); This is the constructor for taking a vector<int> and making it a PhysVec. Our project spec limits the type to int. Recognize this is not unsigned int. You will need to set the instances a_vec_ variable to be the input_vec. // overload the copy constructor3. PhysVec::PhysVec(const PhysVec & rhs}; Just what it says. A copy constructor is used to generate a NEW INSTANCE meaning that a copy of the rhs instance does not already exist. The new instance has the this pointer so use it to set the new instances a_vec_ variable to the a_vec_ vector<int> in rhs. This can be done in one line of code. // overload the copy assignment operator4. PhysVec &operator= (const PhysVec & rhs); More complicated since the two instances already exist and the rhs might be a complex entity. This implementation will require two vector<int> iterators. One a const_iterator and one not. Why? What is const and what is not? One iterator is used for the lhs and one for rhs to do the vector element by element copy. Notice that you are returning an object reference since we started with a pointer to an instance. (thats what the instance name refers to a pointer) so when you return, you will be returning what? An instance pointer. (I will give you a hint this pointer 🙂 ) 5. PhysVec operator+ (const PhysVec & rhs) const ; This is the high point of the PhysVec class. A PhysVes adds the same terms together in two vectors generating a third vector. a_i + b_i = c_i for i = 1 to i= n.This will require three vector iterators, two const_iterators and one non const. You figure out which is which. Based on the function signature you should now realize that you will use the this pointer and the rhs reference. You need to make sure that both vectors are the same length and throw an invalid argument exception with an explanation if not. The tricky part is the vector c. It will be a local, temp vector and you will need to set it to the size of the other two. What is the vector method to do this? Watch out for <vector>.size. It returns a uint_t type not an int. When you add arguments remember that an iterator is a pointer to a vector argument so dereferencing the iterator returns the argument! Also, you are returning the PhysVec vector so that the = operator has the right type to work with. The = operator works with two OBJECTS not OBJECT REFERENCES! Watch the consts. 6. int calculateDotProduct(const PhysVec & rhs) const; https://www.mathsisfun.com/algebra/vectors-dot-product.html Look at this link to figure out dot product if you cannot remember it. The dot product implementation will look a lot like the + operator except the function will be different obviously and since are returning an int, you will only need two iterators. You figure out which type. 7. void setPhysVec(const std::vector<int> & input_vec); This is a setter for a PhysVec. It is used with the default constructor which creates a non const PhysVec. If you are trying to change a const PhysVec you may need to cast the PhysVec as non const to use this function on it. You can always overload this function and make a second non-const taking version too.Read this: https://www.cprogramming.com/tutorial/const_correctness.html This function should be easy by now since you already did the constructor and understand the this pointer. Hint Hint ( I am making this way too easy 🙁 )

// getters for a PhysVec turns a PhysVec into a normal vec

8. std::vector<int> &get_a_vec(); I refuse to lower myself to explain this. 9. void printvecs() const ; To print a vector you need to use an iterator to walk through the elements. Enough said. Submission: You will need to write the implementation .cpp file. You will need to write a main file. Both of these will #include the PhysVec.h file. Because this is your first coding assignment with me, I am giving you the main file I used to test my work. This will likely not happen again. You need to do a much nicer one that has nice comments and tests all the cases since I left at least one or two out so you have to think about it. I will test your code with another main that my grader and I whip up. Hes pretty smart so you might want to consider limits, combinations, error conditions, ect. I want the three files plus your CMakeLists.txt file on TRACS. DO NOT BE LATE! One last thing: If I didnt do something correctly that doesnt mean you can too. You find it, you fix it. I am pretty good at this but you never know, sometimes I put errors in on purpose 🙂 Oh Yeah, One last thing. If you think there is anything missing, you might want to ask in class. Greg