Templates and Operator Overloading in C++

Transcription

1 Templates and Operator Overloading in C++ CSE030 Lab 12 Assignment 12 Tuesday Section (03L) Due Date (100%): November 27 at 1:50pm Resubmission Deadline (50% credit): December 4 at 11:00am Thursday Section (02L) Due Date (100%): November 29 at 10:50am Resubmission Deadline (50% credit): December 6 at 8:00am 1 Description This lab will explore templates and operator overloading in the C++ programming language. The goal of the first part of this lab is to modify the previously-implemented Linked List so that it can now be used to store any data types as opposed to a specific one (integers in our case). This part of the lab will be solved using templates so that our original list of integers can still be used, but with different data types (i.e. doubles, floats, characters, strings, etc...). In second part of the lab, students will explore operator overloading, a powerful but complex technique that allows programmers to define specific functions to operators (i.e. +, -,,!, <<, =, >>, etc...) when used with user-created objects/classes. Once again, the Linked List class will be exploited and a set of operators will be implemented to render the class more user-friendly. WARNING: Your lab will be checked to make sure that you have the right functions implemented as per the lab s description. You have to use the first Linked List class for part 1 (LinkedListP1.h), the Linked List class files for part 2 (LinkedList.h and LinkedList.cpp), and two main files (part1.cpp and part2.cpp) provided on UCMCROPS. YOU ARE NOT to modify the files - simply add code wherever appropriate. Getting 100% with grade me WITHOUT having implementing the right functions will result in getting a 0 for this lab. Note: You need to have a separate program for each part of the lab. When you make a tar ball of your lab assignment to submit through UCMCROPS (see below for more information on how to do that), make sure that ALL PARTS are included. 1

2 2 Getting Started Download the files LinkedListP1.h, LinhkedList.h, LinkedList.cpp, part1.cpp, and part2.cpp. The LinkedListP1.h is the LinkedList class implementation that you will modify so that it becomes a templated class (part 1). The LinkedList.h and LinkedList.cpp files are the LinkedList class implementation for part2, in which you will implement the four overloaded operators. You do not need to modify LinkedList.h. The part1.cpp file is the main file for part1 and the part2.cpp file is the main file for part2. Create a new directory in your main development directory (probably on Desktop/CSE030) called Lab12. Similarly, create a new directory inside Lab12 for each part of this lab (i.e. part1, part2, etc...). Most of you should be able to do this with your eyes closed by now (if not with your eyes closed, you should not need to ask for help from the TA and/or friends). 3 Reminder Once you have created a file and coded its content, you want to compile the source file (i.e. main.cpp) into an executable so that you can run it on your computer. Note: EVERYTIME you modify your source file (i.e. main.cpp), you MUST re-compile your source file for the changes to take effect. You will compile from the command line by running: g++ source -o executable where g++ is a program (already installed on your Linux system) that compiles C++ source files, source is the source file for your program, -o tells the compiler that you want to give the executable its own name, and executable is the name you want to give your program. As an example, if we have a source file (with C++ code inside) called test.cpp and want to create an executable called atestprogram, we would have to run: g++ test.cpp -o atestprogram Assuming that your program compiled successfully (i.e. no errors were found), you can run your program by typing./executable in the terminal/console. Again, looking at the previous example where we created a test program, the command to run it would be./atestprogram. 4 Compiling Classes The g++ syntax to compile classes is slightly different than for a single program comprised of a main (and potential functions): g++ class1.h class1.cpp class2.h class2.cpp mainsource.cpp -o executable 2

3 where g++ is a program (already installed on your Linux system) that compiles C++ source files, mainsource.cpp is the source file for your main program (where the main function is), class1.h is the class skeleton/declaration for your 1st class, class1.cpp is your 1st class implementation, class2.h is the class skeleton/declaration for your 2nd class, class2.cpp is your 2nd class implementation (and so on...), -o tells the compiler that you want to give the executable its own name, and executable is the name you want to give your program. As an example, if we have a main source file called main.cpp, the class skeleton/declaration called Time.h, the class implementation called Time.cpp, and want to create an executable called atestprogram, we would have to run: g++ Time.h Time.cpp main.cpp -o atestprogram Assuming that your program compiled successfully (i.e. no errors were found), you can run your program as you normally would by typing./executable in the terminal/console. Again, looking at the previous example where we created a test program, the command to run it would be./atestprogram. 5 Part 1 (8 pts) In this part of the lab, you will modify LinkedListP1.h and part1.cpp in such a way that the original Linked List, which only worked for integers, will be templated and consequently work for any data type (string, char, double, etc...). Since the class is already provided for you (and you have already implemented a Linked List specifically for integers), templating it is quite straightforward. More specifically, you need to modify the LinkedListP1.h and add the construct template class T before any class declaration, structure declaration, and function declaration. The construct tells C++ that it can use any data type (defined by T) as part of the class. This means that if you want a Linked List of type int, then T will represent an int. If you want a Linked List of type string, then T will represent a string. Once you have added the construct in front of every structure declaration, class declaration, and function declaration, you need to modify the code to take into account that we will now use T (which represents the data type) instead of int. This means that every time int is used for the LinkedList values, you will replace it by T. Finally, every time you use a templated structure or class, you need to add T in the class and datatype in the main file (where datatype is int, string, etc...). In otherwords, if you have a templated class called Array, you will need to use Array T where ever appropriate inside the class and Array double inside the main file. To summarize, templating the Linked List class is comprised of 4 steps: 1) Inside LinkedListP1.h, add the construct template class T in front of every structure declaration, class declaration, and function declaration. 2) Modify LinkedListP1.h, so that it uses T as the data type for its values (instead of int). 3) Modify LinkedListP1.h, so that whenever a Node or a LinkedList is used (even namespaces!), it is used as a template (i.e. Node T or LinkedList T ). 3

4 4) Modify the first 4 lines of part1.cpp, so that the appropriate LinkedList type is created (see comments). As always, make sure you follow EXACTLY the output structure given in the examples. 5.1 Example 1 The first list is empty! The second list is empty! The third list is empty! The fourth list is empty! The size of the first list is: 0 The size of the second list is: 0 The size of the third list is: 0 The size of the fourth list is: 0 Here is the first list: [10,-1,1] Here is the second list: [ ,0.7775,1.454] Here is the third list: [Ben,Stefano] Here is the first list: [10,-1,1] Here is the second list: [ ,0.7775,1.454] Here is the third list: [Ben,Stefano] Here is the fourth list: [C,S,E] Here is the first list: [-1,1] Here is the second list: [] Here is the third list: [Ben,Stefano] Here is the fourth list: [C,S,E] Here is the first list: [] Here is the second list: [] Here is the third list: [Teaching Assistant,Professor,Ben,Stefano] Here is the fourth list: [C,S,E,2,0] The size of the first list is: 0 The size of the second list is: 0 The size of the third list is: 4 The size of the fourth list is: 5 The first list is empty! The second list is empty! Here is the fourth list: [C,S,E,2,0] Here is the fourth list: [S,E,2,0] Here is the fourth list: [S,E,2] 4

5 Here is the fourth list: [E,2] Here is the fourth list: [E] COULD NOT remove an item from the list! COULD NOT remove an item from the list! The size of the first list is: 0 The size of the second list is: 0 The size of the third list is: 4 The size of the fourth list is: 0 The first list is empty! The second list is empty! The fourth list is empty! 5.2 Grade Me Command Use the following command to grade this project: grade me lab12 part1 executable where executable is the name of your compiled program. 6 Part 2 (8 pts) In this part of the lab you will add overloaded operators to your LinkedList. Download the files LinkedList.h, LinkedList.cpp, and part2.cpp. You DO NOT need to modify LinkedList.h and part2.cpp. You simply need to fill in the overloaded operators inside LinkedList.cpp. Specifically, you need to write code for the following overloaded operators: LinkedList& operator=(linkedlist& rhs): this is the equal operator that allows one LinkedList to be assigned to another (using the form list1 = list2;). In this function (or overloaded operator), you should take the content of the right hand side of the equation (list2 in the example, which is defined by the parameter rhs) and assign it to the left-hand side (list1 in this example). You have access to the left-hand side of the equation by using the this keyword. Hint: You can use any functions that have already been implemented. Use the functions to make your life/coding simpler. Hint: Make sure that you clear/empty the list on the left hand side of the equation before you do anything. Hint: Be careful and take into account self-assignment (i.e., list1=list1). The list should 5

6 not be modified in that case. LinkedList& operator+=(linkedlist& rhs): the += operator appends the list on the right-hand side of the equation to the one on the right hand side of the equation (list1+=list2). Once again, the parameter passed into the function, rhs, is the right-hand side of the equation (list2 in the example) and you can use the keyword this to access the left-hand side of the equation (part1). Note: Once again, be careful with self-assignments (list1+=list1;). Hint: You can use any functions that have already been implemented. Use the functions to make your life/coding simpler. void operator (): This is a unary operator that we will use to clear/empty the linked list ( list1;). Unary operators do not take any parameters and you can access the list (list1 in this example) by using the keyword this. Hint: This is a very simple function that should only be one line. friend ostream &operator<<(ostream &out, LinkedList& rhs): This operator allows you to print your object directly onto the screen. This is a special operator in that it must be a friend of your class so that the ostream (output stream) can be accessed. With this operator, you will print out the list to the screen. 6.1 Example 1 Here is the first list: [1,2,3,4,5,6,7] Here is the second list: [10,5,0,-5] Here is the third list: [8,9,10,11] Here is the first list: [1,2,3,4,5,6,7] Here is the second list: [10,5,0,-5] Here is the third list: [8,9,10,11] Here is the fourth list: [1,2,3,4,5,6,7] Here is the first list: [1,2,3,4,5,6,7] Here is the second list: [10,5,0,-5] Here is the third list: [10,5,0,-5] Here is the fourth list: [1,2,3,4,5,6,7,8,9,10,11] Here is the first list: [1,2,3,4,5,6,7,8,9,10,11] 6

7 Here is the second list: [1,2,3,4,5,6,7,8,9,10,11] Here is the third list: [1,2,3,4,5,6,7,8,9,10,11] Here is the fourth list: [1,2,3,4,5,6,7,8,9,10,11] Here is the first list: [1,2,3,4,5,6,7,8,9,10,11] Here is the second list: [1,2,3,4,5,6,7,8,9,10,11] Here is the third list: [] Here is the first list: [1,2,3,4,5,6,7,8,9,10,11,1,2,3,4,5,6,7,8,9,10,11] Here is the second list: [1,2,3,4,5,6,7,8,9,10,11,1,2,3,4,5,6,7,8,9,10,11] Here is the third list: [] 6.2 Grade Me Command Use the following command to grade this project: grade me lab12 part2 executable where executable is the name of your compiled program. 7 Your solutions Before leaving the lab, make sure that you have received credit (full or partial) from the grade me program for the parts of the assignment. Submit a tar ball of your program through the assignments page of UCMCROPS. Please follow the following naming convention for your submissions: LastName FirstName.tar In order to tar a folder named Lab12, please execute the following command in a terminal: tar cvf LastName FirstName.tar Lab12 Be careful since UCMCROPS strictly enforces the assignment deadlines (deadlines will be at the end of the lab). Note: You need to have a separate program for each of the parts of this lab. When you make the tar ball of your lab assignment to submit through UCMCROPS, make sure that ALL PARTS are included. 7