This assignment is an exercise in implementing the stack ADT using a singly-linked list. This assignment also introduces the concept of templates.

Assignment

This program creates and implements a class to represent the Stack ADT using a singly-linked list.

A driver program is provided for this assignment to test your implementation. You don't have to write the tests.

Program

You will need to write one template structure and one template class for this assignment, called Node and Stack. You will need to implement several methods and functions associated with these data types.

Since these are both C++ templates and are closely related to each other, all of your code should be placed in a single header (.h) file. This includes the implementations of all methods and any other associated functions.

struct Node

Data members

This template structure should have two data members: a member of the template parameter type to store an item to be inserted into the stack, and a pointer to a Node. This pointer, next, will point to the next node in the linked list (or be nullptr if this is the last node in the list).

Since the Stack class will need access to these data members, make them public (which is the default for a struct).

Methods

Constructor

The structure should have a constructor that can be used to initialize the data members of the stack node.

class Stack

Data members

This class should have two data members. The first is a pointer to an Node. This pointer, stkTop, will point to the first node in the list, i.e. the top node in the stack (or will be nullptr if the stack is empty). The second data member should be an size_t or unsigned integer that will be used to store the stack size, the number of items currently stored in the stack.

Methods and associated functions

Constructor

The class should have a default constructor that takes no arguments. The constructor should set stkTop to nullptr and set the stack size to 0.

Destructor

The class should have a destructor. The destructor can simply call the clear() method described below.

Copy constructor

The class should also have a proper copy constructor.

operator=

The assignment operator should be properly overloaded.

operator<<

The output operator should be overloaded so that an entire Stack can be sent to the standard output. As usual, this function will need to be a friend rather than a method. Declaring a template function to be a friend of a template class requires some special syntax - see the Implementation Hints below.

clear()

This method takes no arguments and returns nothing. It should properly set the stack back to the empty state. That means deleting all of the nodes in the stack, setting the top pointer back to nullptr, and setting the stack size back to 0. One easy way to accomplish this is to repeatedly pop until the stack is empty.

size()

This method takes no arguments and returns an unsigned integer or size_t. It should return the stack size; i.e., the number of data items currently stored in the stack.

empty()

Returns true if there are no data items currently stored in the stack; otherwise returns false.

top()

This method takes no arguments and returns a reference to a constant item of the template parameter type. It should return the data stored in the top node of the stack (i.e., the first node in the linked list). You may assume this method will not be called if the stack is empty.

push()

This method takes a reference to a constant item of the template parameter type as its argument (the item to insert into the stack). It returns nothing. The method should insert the item at the top of the stack (at the front of the linked list).

pop()

This method takes no arguments and returns nothing. It should remove the node at the top of the stack. You may assume this method will not be called if the stack is empty.

If you like, you may write private methods for the Stack class in addition to the methods described above. For example, you may want to write a copyList() method that can be called by both the copy constructor and overloaded assignment operator to make a copy of the linked list.

Driver Program

A driver program, assign7.cpp is provided for this assignment. The purpose of a driver program is to test other pieces that you code. You do not need to write the driver program yourself. A copy of the driver program can also be found on turing at /home/turing/t90kjm1/CS241/Code/Spring2017/Assign7/assign7.cpp.

/********************************************************************* PROGRAM: PROGRAMMER: your name LOGON ID: DUE DATE: due date of assignment FUNCTION: This program tests the functionality of the Stack template class. *********************************************************************/ #include "Stack.h" #include  using std::cout; using std::endl; int main() { cout << "Testing default constructor "; Stack s1; cout << "s1 (size " << s1.size() << "): " << s1 << endl; cout << "s1 is " << ((s1.empty()) ? "empty " : "not empty "); cout << endl; cout << "Testing push() "; s1.push(17); cout << "s1 (size " << s1.size() << "): " << s1 << endl; cout << "s1 is " << ((s1.empty()) ? "empty " : "not empty "); cout << endl; s1.push(2); s1.push(6); s1.push(4); cout << "s1 (size " << s1.size() << "): " << s1 << endl; cout << "s1 is " << ((s1.empty()) ? "empty " : "not empty "); cout << endl; cout << "Testing copy constructor "; Stack s2(s1); cout << "s1 (size " << s1.size() << "): " << s1 << endl; cout << "s2 (size " << s2.size() << "): " << s2 << endl << endl; cout << "Testing clear() "; s1.clear(); cout << "s1 (size " << s1.size() << "): " << s1 << endl; cout << "s2 (size " << s2.size() << "): " << s2 << endl << endl; Stack s3; s3.push(36); s3.push(41); s3.push(75); s3.push(28); cout << "s3 (size " << s3.size() << "): " << s3 << endl << endl; cout << "Testing assignment operator "; Stack s4; s4 = s3; cout << "s3 (size " << s3.size() << "): " << s3 << endl; cout << "s4 (size " << s4.size() << "): " << s4 << endl << endl; s3.clear(); cout << "s3 (size " << s3.size() << "): " << s3 << endl; cout << "s4 (size " << s4.size() << "): " << s4 << endl << endl; cout << "Testing assignment to self "; s4 = s4; s3 = s4; s4.clear(); cout << "s3 (size " << s3.size() << "): " << s3 << endl; cout << "s4 (size " << s4.size() << "): " << s4 << endl << endl; cout << "Testing chained assignment "; Stack s5; s5 = s4 = s3; cout << "s3 (size " << s3.size() << "): " << s3 << endl; cout << "s4 (size " << s4.size() << "): " << s4 << endl; cout << "s5 (size " << s5.size() << "): " << s5 << endl << endl; cout << "Testing top(), push(), pop() "; Stack s6, s7; for(char c = 'a'; c < 'k'; c++) s6.push(c); cout << "s6 (size " << s6.size() << "): " << s6 << endl << endl; for(int i = 0; i < 10; i++) { int val; val = s6.top(); s7.push(val); s6.pop(); } cout << "s6 (size " << s6.size() << "): " << s6 << endl; cout << "s7 (size " << s7.size() << "): " << s7 << endl << endl; cout << "Testing top() "; s6 = s7; int val1 = s6.top(); int val2 = s7.top(); val1 = s6.top(); // Make sure that top() doesn't remove a value. cout << ((val1 == val2) ? "top() works " : "top() failure "); cout << "Testing const correctness "; s7.clear(); const Stack& r6 = s6; cout << "s6 (size " << r6.size() << "): " << r6 << endl; cout << "s6 is " << ((r6.empty()) ? "empty " : "not empty "); cout << "Top item of s6: " << r6.top() << endl << endl; s7 = r6; Stack s8(r6); cout << "s7 (size " << s7.size() << "): " << s7 << endl; cout << "s8 (size " << s8.size() << "): " << s8 << endl << endl; return 0; } 

Output

Output from the correctly functioning driver program should look like the following:

Testing default constructor s1 (size 0): s1 is empty Testing push() s1 (size 1): 17 s1 is not empty s1 (size 4): 4 6 2 17 s1 is not empty Testing copy constructor s1 (size 4): 4 6 2 17 s2 (size 4): 4 6 2 17 Testing clear() s1 (size 0): s2 (size 4): 4 6 2 17 s3 (size 4): 28 75 41 36 Testing assignment operator s3 (size 4): 28 75 41 36 s4 (size 4): 28 75 41 36 s3 (size 0): s4 (size 4): 28 75 41 36 Testing assignment to self s3 (size 4): 28 75 41 36 s4 (size 0): Testing chained assignment s3 (size 4): 28 75 41 36 s4 (size 4): 28 75 41 36 s5 (size 4): 28 75 41 36 Testing top(), push(), pop() s6 (size 10): j i h g f e d c b a s6 (size 0): s7 (size 10): a b c d e f g h i j Testing top() top() works Testing const correctness s6 (size 10): a b c d e f g h i j s6 is not empty Top item of s6: a s7 (size 10): a b c d e f g h i j s8 (size 10): a b c d e f g h i j 

Implementation Hints

Implement this similarly to the last assignment. Start off at the beginning of the driver program and try to get it working piece by piece. Maintain a working program as you go.

Declaring a template function to be a friend of a template class is one of the classic "gotcha's" in C++. We are trying to declare a function to be a friend of all classes that might be instantiated from the Stack template class, and most C++ compilers will quite properly refuse to do that without some special syntax.

The friend declaration must contain an extra set of <> to indicate that it is a template function (however, do not code this in the actual function definition - only the friend declaration). You'll also usually need to forward declare both the template class and the template function, as shown below.

How much of this you actually need to do can vary from compiler to compiler, but the code shown below should work in Quincy, Dev-C++, and with g++ on turing/hopper.

#ifndef STACK_H #define STACK_H #include  template  struct Node { ... }; // Method definitions for the Node class // Forward declaration of the Stack template class template  class Stack; // Forward declaration of the operator<< template function template  std::ostream& operator<<(std::ostream&, const Stack&); template  class Stack { // friend declaration for the template function - note the // special syntax friend std::ostream& operator<< <>(std::ostream&, const Stack&); ... }; // Method definitions for the Stack class #endif /* STACK_H */