0

I recently wrote an implementation of STL Vector as a programming exercise. The program compiles but I receive a strange error saying:

```
terminate called after throwing an instance of 'std::bad_alloc'
what(): std::bad_alloc
```

I've never come up with this error before and am not sure what exactly should be changed within my implementation to make it function correctly.

Can someone take a look through my code and see if anything jumps out at them as wrong in this specific case? I am sure that the problem is either in my push_back function or in my copy constructor. thanks in advance.

```
#include <iostream>
#include <string>
#include <cassert>
#include <algorithm>
#include <cstring>
using namespace std;
template <class T>
class Vector
{
public:
typedef T * iterator;
Vector();
Vector(unsigned int size);
Vector(unsigned int size, const T & initial);
Vector(const Vector<T> & v); // copy constructor//Done
~Vector();
unsigned int capacity() const; // return capacity of vector (in elements)//Done
unsigned int size() const; // return the number of elements in the vector//Done
bool empty() const;
iterator begin(); // return an iterator pointing to the first element // Done
iterator end(); // return an iterator pointing to one past the last element //Done
T & front(); // return a reference to the first element //Done
T & back(); // return a reference to the last element //Done
void push_back(const T & value); // add a new element //Done
void pop_back(); // remove the last element //Done
void reserve(unsigned int capacity); // adjust capacity //Done
void resize(unsigned int size); // adjust size //Done
T & operator[](unsigned int index); // return reference to numbered element
Vector<T> & operator=(const Vector<T> &);
private:
unsigned int my_size;
unsigned int my_capacity;
T * buffer;
};
template<class T>//
Vector<T>::Vector()
{
my_capacity = 0;
my_size = 0;
buffer = 0;
}
template<class T>
Vector<T>::Vector(const Vector<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>//
Vector<T>::Vector(unsigned int size)
{
my_capacity = size;
my_size = size;
buffer = new T[size];
}
template<class T>//
Vector<T>::Vector(unsigned int size, const T & initial)
{
my_size;
my_capacity = size;
buffer = new T [size];
for (int i = 0; i < size; i++)
buffer[i] = initial;
}
template<class T>//
Vector<T> & Vector<T>::operator = (const Vector<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>//
typename Vector<T>::iterator Vector<T>::begin()
{
return buffer;
}
template<class T>//
typename Vector<T>::iterator Vector<T>::end()
{
return buffer + size();
}
template<class T>//
T& Vector<T>::Vector<T>::front()
{
return buffer[0];
}
template<class T>//
T& Vector<T>::Vector<T>::back()
{
return buffer[size - 1];
}
template<class T>
void Vector<T>::push_back(const T & v)
{
if (my_size >= my_capacity)
reserve(my_capacity +5);
buffer [my_size++] = v;
}
template<class T>//
void Vector<T>::pop_back()
{
my_size--;
}
template<class T>//
void Vector<T>::reserve(unsigned int capacity)
{
if(buffer == 0)
{
my_size = 0;
my_capacity = 0;
}
if (capacity <= my_capacity)
return;
T * new_buffer = new T [capacity];
assert(new_buffer);
copy (buffer, buffer + my_size, new_buffer);
my_capacity = capacity;
delete[] buffer;
buffer = new_buffer;
}
template<class T>//
unsigned int Vector<T>::size()const
{
return my_size;
}
template<class T>//
void Vector<T>::resize(unsigned int size)
{
reserve(size);
my_size = size;
}
template<class T>//
T& Vector<T>::operator[](unsigned int index)
{
return buffer[index];
}
template<class T>//
unsigned int Vector<T>::capacity()const
{
return my_capacity;
}
template<class T>//
Vector<T>::~Vector()
{
delete[]buffer;
}
int main()
{
Vector<int> v;
v.reserve(2);
assert(v.capacity() == 2);
Vector<string> v1(2);
assert(v1.capacity() == 2);
assert(v1.size() == 2);
assert(v1[0] == "");
assert(v1[1] == "");
v1[0] = "hi";
assert(v1[0] == "hi");
Vector<int> v2(2, 7);
assert(v2[1] == 7);
Vector<int> v10(v2);
assert(v10[1] == 7);
Vector<string> v3(2, "hello");
assert(v3.size() == 2);
assert(v3.capacity() == 2);
assert(v3[0] == "hello");
assert(v3[1] == "hello");
v3.resize(1);
assert(v3.size() == 1);
assert(v3[0] == "hello");
Vector<string> v4 = v3;
assert(v4.size() == 1);
assert(v4[0] == v3[0]);
v3[0] = "test";
assert(v4[0] != v3[0]);
assert(v4[0] == "hello");
v3.pop_back();
assert(v3.size() == 0);
Vector<int> v5(7, 9);
Vector<int>::iterator it = v5.begin();
while (it != v5.end())
{
assert(*it == 9);
++it;
}
Vector<int> v6;
v6.push_back(100);
assert(v6.size() == 1);
assert(v6[0] == 100);
v6.push_back(101);
assert(v6.size() == 2);
assert(v6[0] == 100);
v6.push_back(101);
cout << "SUCCESS\n";
}
```