c++ using vector of employee pointers - c++

Question

I have created my vector class template and I have already done my employee classes of hourly and I salaried. I want to use the vector of employee pointers instead of the array of employee pointers, I'm trying to do that but when I run it just breaks while I have no error listed.
Also, I have used the at function like( payroll.at(i)->writeFile(out); ) to get access to an element, but I don't know what's wrong.
Any suggestion?
Thanks
here is my code:
myvector class template:
#include <iostream>
#include <string>
#include <cassert>
#include <algorithm>
const int CAPACITY = 4;
template <class T>
class MyVector {
public:
MyVector();
MyVector( int size);
MyVector( int size, const T & initial);
MyVector(const MyVector<T> & v);
~MyVector();
int capacity() const;
int size() const;
void push_back(const T & value);
//T & operator[](unsigned int index);
MyVector<T> & operator=(const MyVector<T> &);
void clear();
T at(int i);
friend ostream& operator<<(ostream &out, const MyVector<T>& );
private:
int applied;
int my_size;
int my_capacity;
T * buffer;
T * daArray;
};
template<class T>
MyVector<T>::MyVector()
{
my_capacity = 0;
my_size = 0;
buffer = 0;
applied = 0;
}
template<class T>
MyVector<T>::MyVector(const MyVector<T> & v)
{
my_size = v.my_size;
my_capacity = v.my_capacity;
buffer = new T[my_size];
for ( int i = 0; i < my_size; i++)
buffer[i] = v.buffer[i];
}
template<class T>
MyVector<T>::MyVector(int size)
{
my_capacity = size;
my_size = size;
buffer = new T[size];
}
template<class T>
MyVector<T>::MyVector( int size, const T & initial)
{
my_size = size;
my_capacity = size;
buffer = new T [size];
for (unsigned int i = 0; i < size; i++)
buffer[i] = initial;
//T();
}
template<class T>
MyVector<T> & MyVector<T>::operator = (const MyVector<T> & v)
{
delete[ ] buffer;
my_size = v.my_size;
my_capacity = v.my_capacity;
buffer = new T [my_size];
for (int i = 0; i < my_size; i++)
buffer[i] = v.buffer[i];
return *this;
}
template<class T>
void MyVector<T>::push_back(const T & i)
{
if (my_capacity == 0)
{
my_capacity = 1;
my_size = 1;
applied= 0;
buffer = new T[1];
buffer[0] = i;
}
else
{
if (applied+1 == my_capacity)
{
int newCapacity = my_capacity * CAPACITY;
daArray = new T[newCapacity];
for (int i = 0; i < my_size; i++)
{
daArray[i] = buffer[i];
}
my_capacity = newCapacity;
delete buffer;
my_size++;
applied++;
buffer[applied] = i;
}
else
{
if (my_size == applied + 1)
my_size++;
applied++;
buffer[applied] = i;
}
}
}
template<class T>
int MyVector<T>::size()const//
{
return my_size;
}
template<class T>
int MyVector<T>::capacity()const
{
return my_capacity;
}
template<class T>
MyVector<T>::~MyVector()
{
delete[ ] buffer;
}
template <class T>
void MyVector<T>::clear()
{
my_capacity = 0;
my_size = 0;
buffer = 0;
}
template <class T>
T MyVector<T>::at(int i)
{
if (i < 0 || i > my_size -1)
{
string error = "Index is undefined";
throw error;
}
return buffer[i];
}
template <class T>
ostream& operator<<(ostream &out, const MyVector<T>& v)
{
for (unsigned i = 0; i < v.size(); i++)
{
out << v[i] << " ";
}
return out;
}
main
int main() {
MyVector< employee*> payroll;
payroll.push_back(new Hourly ("H. Potter", "Privet Drive", "201-9090", 40, 12.00));
payroll.push_back(new Salaried ( "A. Dumbledore", "Hogewarts", "803-1230", 1200));
ofstream out;
out.open(file);
if (out.fail()) {
cout<<" could not open the file"<<endl;
system("PAUSE");
}
for (int i = 0; i < SIZE; i++) {
payroll.at(i)->writeFile(out);
}
out.close( );
}

Answer 1

You have a bug in your push_back method. You need something like this
if (applied+1 == my_capacity)
{
int newCapacity = my_capacity * CAPACITY;
daArray = new T[newCapacity];
for (int i = 0; i < my_size; i++)
{
daArray[i] = buffer[i];
}
my_capacity = newCapacity;
delete buffer;
buffer = daArray; // new line here
my_size++;
applied++;
buffer[applied] = i;
}
See where I've put the comment // new line here