Stack and Queues questions

I am preparing for a test and have answered some questions dealing with stacks and queues the teacher has provided as samples. Could someone check over my work?

Code:

// stack.h – complete header file for Stack ADT
#include <iostream>
using namespace std;

class StackFull { /* Empty Exception Class */ };
class StackEmpty { /* Empty Exception Class */ };
class Stack // An array implementation of Stack ADT for storing integers
{
private:
int* ptr; // Holds address of dynamically-allocated integer array
int top; // Array index of top-most integer on the stack
int size; // Maximum number of integers that may be stored in the stack

public:
Stack(int num); // Dynamically allocate 1-D array of integers of size num
                        // and configure empty stack
~Stack(); // Deallocates stack array
void Push(int n); // Add integer n to the top of the stack if not full
                          // Otherwise, throw StackFull exception
int Pop(); // Removes top integer from stack AND returns value to
               // client; throws StackEmpty exception if stack is empty
void MakeEmpty(); // Return stack to empty but usable state
bool IsFull() const; // Return true if stack is full; otherwise return false
bool IsEmpty() const; // Return true if stack is empty; otherwise return false
int Capacity() const; // Returns the maximum number of integers that may be
                                // stored in Stack object
}; // End Class Stack

1) Implement Stack.

Code:

Stack::Stack(int num)
{
 ptr=new int[num];
 top=0;
 size=num;
}

2) Implement Push method

Code:

void Stack::Push(int n)
{
 if(IsEmpty() )
   throw StackFull();
 else
 {
  ptr[top]=n;
  top++;
 }
}

3) Implement IsEmpty

Code:

bool Stack::IsEmpty() const
{
 return (top == 0);
}

4) Implement Pop

Code:

int Stack::Pop()
{
 if (IsEmpty())
   throw StackEmpty();
 else
 {
  int temp=ptr[top];
  top--;
  return temp;
 }
}

5) Implement Desctructor

Code:

Stack::~Stack()
{
 MakeEmpty();
}

6) Implement Capacity

Code:

int Stack::Capacity() const
{
 return size;
}

7) Implement IsFull

Code:

bool Stack::IsFull() const
{
 return (top == size);
}

Have you tested the code? It seems to have a pretty big bug which you should find easily.

Other than that, such classes also require a user-defined copy constructor and assignment operator to perform a deep copy.

Also you haven't shown the implementation of MakeEmpty. If it does what the comment suggests, then I don't see how the destructor can avoid a leaking memory.

You need to provide your own copy constructor/operator, or make this class non-copyable (inherit from boost::noncopyable).

The header code was provided and the questions 1-7 were multiple choice questions I had to answer. I am not writing specific code, just using the header to write a few functions. Just wanted to check and see if I got each one right.

Oh, so these points were actually questions.
You still have a bug in one of your method - the Pop() method.

Originally Posted by kmdv

Oh, so these points were actually questions.
You still have a bug in one of your method - the Pop() method.

Correct. Just had to chose between four sample codes provided or None of the above, because it is a multiple choice question. Are the others correct except Pop?

Implement Pop

Code:

int Stack::Pop()
{
 if (IsEmpty())
   throw StackEmpty();
 else
 {
  return ptr[top];
  top--;
 }
}

int Stack::Pop()

O_o

You have no idea how much seeing that upsets me.

Anyway, anon wasn't teasing you. You have a big bug and it isn't localized to any one function.

Put the code into a testbed and see what happens.

Soma

Originally Posted by phantomotap

O_o

You have no idea how much seeing that upsets me.

Anyway, anon wasn't teasing you. You have a big bug and it isn't localized to any one function.

Put the code into a testbed and see what happens.

Soma

Read the other posts. This is not code I am testing. Those 1-7 were questions are dealing with the header file up top.

why does seeing that upset you?

anyways for the int pop..if the first if statement part executes you need to return something..that is one bug

also looks like you don't clean up after yourself..so I assume that option is incorrect

why does seeing that upset you?

Let me just say that in real life C++ stack implementations such a signature causes a problem.

Read the other posts. This is not code I am testing.

I'm well aware. If you threw the code at a testbed you would know that those options are the wrong ones and have an idea about what the right ones would look like.

Soma

@phantomtap: It is unclear whether such a signature causes a problem here.

@OP: Which part is your answer? There appear to be bugs in both Push and Pop. These are your code?

Originally Posted by anon

@phantomtap: It is unclear whether such a signature causes a problem here.

@OP: Which part is your answer? There appear to be bugs in both Push and Pop. These are your code?

Not my code, for each question there are 4 code options to choose from and also 'none of the above'. So for those, pop and push, I have chose the incorrect one. When I get back I will try to chose the correct one and post it. Most choices are very similar with just 1-2 lines different.

Originally Posted by anon

@phantomtap: It is unclear whether such a signature causes a problem here.

@OP: Which part is your answer? There appear to be bugs in both Push and Pop. These are your code?

Here is my correction for Push and Pop.

Implement Push

Code:

void Stack::Push(int n)
 if (IsFull())
  throw StackFull();
 else
 {
  top++;
  ptr[top]=n;
 }
}

Implement Pop

Code:

int Stack::Pop()
{
 if (IsEmpty())
  throw StackEmpty();
 else
 {
  top--;
  return ptr[top];
 }
}