Overloading operators in C++

1. [C]

   Create a directory ~/PDC/hw2 on a Link machine for your work on this homework assignment.

2. [C]

   Implement and test a class Mvector that satisfies the spec provided.

   Implement your class in files Mvector.h and Mvector.cpp, and test it with a program MvectorTest.cpp. Include a Makefile for building your program.

   Notes:

   • Reminder: A Makefile describes how to compile and link software. Makefiles include rules for carrying out one step in building your program. For example,
     
     is a Makefile rule.

     • Mvector.o is the target file to be produced by that rule.

     • Mvector.cpp and Mvector.h are the prerequisites in that rule.
       If any of the prerequisites change, then the target Mvector.o must be regenerated.

     • g++ -c Mvector.cpp is the action in that rule, a shell command for producing the target Mvector.o. There maybe multiple action lines for a given target.
       Each action line must be preceded by a TAB character.

     You will need three rules: one for compiling Mvector.o; one for compiling MvectorTest.o; and one for linking those two .o files to create an executable MvectorTest.

   • When implementing Mvector, use dynamic allocation for the state variable arr[], and correct memory management throughout your class definition.

   • Define default_len (needed for default constructor) as an int class variable in Mvector, i.e., a state variable with class scope (static). Be sure to define that class variable outside of the class definition for Mvector -- not in a header file (perhaps named Mvector.h) but in an implementation module (perhaps Mvector.cpp).

   • Use C++'s cassert feature to cause the program to crash when a method is called incorrectly. For example, you can implement the method operator[ ] for this class as follows:

         #include <cassert>
         ...
         float &Mvector::operator[](int index) {
           assert(0 <= index && index < len);
           return arr[index];
         }
     

     Then, if vec is an Mvector object, a call such as vec[-1] will cause the program to abort execution and print a useful error message that involves the expression 0 <= index && index < len .

   • Here are sample calls of the * and + operators for Mvector. Assume that vec, vec1, etc., are Mvector objects with appropriate lengths.

         vec = vec1 * 3;
         vec = vec1 * vec2;
         vec = vec1 + vec2;
     

   • In your test code, use operator[] to assign values to Mvector objects. For example,

         Mvector vec(5);
         vec[2] = 3.14;
     

     assigns the value 3.14 to the third element in vec.arr[] .

     To check whether your vector operations are producing correct answers, it will help to define a function or method dump() that prints all of the values in a Mvector object in a readable format.

3. [C]

   Implement and test a class Poly that satisfies the spec provided. Poly is a subclass of Mvector that adds a single operator, operator(), which enables a Poly object p to be called as if it were a function (while still providing all the Mvector operations such as *).

   Example call:

       Poly p(4);
       p[0] = 9;
       p[1] = 4;
       p[2] = 6;
       p[3] = 7;
       // p.arr[] now contains four float values 9.0, 4.0, 6.0, and 7.0
   
       cout <<  p(10)  << endl;
       // prints 7.0*103 + 6.0*102 + 4.0*101 + 9.0 = 7649.0
   

Submitting this homework

Submit your work using git on a Link computer.

    #  cd ~/PDC
    #  git pull origin master
    #  git add -A
    #  git commit -m "HW2 submit (link)"
    #  git push origin master

Also, fill out this form to report on your work.