# Adding Functions to an Implementation of Vector

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Meursault
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Published on 2011-03-02T15:14:21Z
Indexed on
2011/03/02
15:24 UTC

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I have this implementation of vector that I've been working on for a few days using examples from a textbook:

```
#include <iostream>
#include <string>
#include <cassert>
#include <algorithm>
#include <cstring>
// Vector.h
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
~Vector();
unsigned int capacity() const; // return capacity of vector (in elements)
unsigned int size() const; // return the number of elements in the vector
bool empty() const;
iterator begin(); // return an iterator pointing to the first element
iterator end(); // return an iterator pointing to one past the last element
T & front(); // return a reference to the first element
T & back(); // return a reference to the last element
void push_back(const T & value); // add a new element
void pop_back(); // remove the last element
void reserve(unsigned int capacity); // adjust capacity
void resize(unsigned int size); // adjust size
void erase(unsigned int size); // deletes an element from the vector
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 = size; //added = 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;
}
template<class T>
void Vector<T>::erase(unsigned int size)
{
}
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";
}
```

So far it works pretty well, but I want to add a couple of functions to it that I can't find examples for, a SWAP function that would look at two elements of the vector and switch their values and and an ERASE function that would delete a specific value or range of values in the vector. How should I begin implementing the two extra functions?

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