La tarea es implementar una clase de vector personalizada similar al vector STL con las siguientes funciones:
- int push_back (datos): agrega un elemento (de cualquier tipo de datos) al final de la array y también devuelve la cantidad de elementos en ese vector
- data_type pop_back(): elimina un elemento del final de la array, también devuelve el elemento reventado
- int size() const: devuelve el tamaño actual del vector
El siguiente programa implementa una clase de vector personalizada en C++ con las funcionalidades mencionadas anteriormente:
CPP14
// C++ program to implement Custom Vector
// class
#include "iostream"
#define ll long long
using namespace std;
// Template class to create vector of
// different data_type
template <typename DT>
class GenericMyVector {
private:
DT* arr;
// Variable to store the current capacity
// of the vector
ll capacity;
// Variable to store the length of the
// vector
ll length;
public:
explicit GenericMyVector(ll = 100);
// Function that returns the number of
// elements in array after pushing the data
ll push_back(DT);
// function that returns the popped element
DT pop_back();
// Function that return the size of vector
ll size() const;
DT& operator[](ll);
// Iterator Class
class iterator {
private:
// Dynamic array using pointers
DT* ptr;
public:
explicit iterator()
: ptr(nullptr)
{
}
explicit iterator(DT* p)
: ptr(p)
{
}
bool operator==(const iterator& rhs) const
{
return ptr == rhs.ptr;
}
bool operator!=(const iterator& rhs) const
{
return !(*this == rhs);
}
DT operator*() const
{
return *ptr;
}
iterator& operator++()
{
++ptr;
return *this;
}
iterator operator++(int)
{
iterator temp(*this);
++*this;
return temp;
}
};
// Begin iterator
iterator begin() const;
// End iterator
iterator end() const;
};
// Template class to return the size of
// vector of different data_type
template <typename DT>
GenericMyVector<DT>::GenericMyVector(ll n)
: capacity(n), arr(new DT[n]), length(0)
{
}
// Template class to insert the element
// in vector
template <typename DT>
ll GenericMyVector<DT>::push_back(DT data)
{
if (length == capacity) {
DT* old = arr;
arr = new DT[capacity = capacity * 2];
copy(old, old + length, arr);
delete[] old;
}
arr[length++] = data;
return length;
}
// Template class to return the popped element
// in vector
template <typename DT>
DT GenericMyVector<DT>::pop_back()
{
return arr[length-- - 1];
}
// Template class to return the size of
// vector
template <typename DT>
ll GenericMyVector<DT>::size() const
{
return length;
}
// Template class to return the element of
// vector at given index
template <typename DT>
DT& GenericMyVector<DT>::operator[](ll index)
{
// if given index is greater than the
// size of vector print Error
if (index >= length) {
cout << "Error: Array index out of bound";
exit(0);
}
// else return value at that index
return *(arr + index);
}
// Template class to return begin iterator
template <typename DT>
typename GenericMyVector<DT>::iterator
GenericMyVector<DT>::begin() const
{
return iterator(arr);
}
// Template class to return end iterator
template <typename DT>
typename GenericMyVector<DT>::iterator
GenericMyVector<DT>::end() const
{
return iterator(arr + length);
}
// Template class to display element in
// vector
template <typename V>
void display_vector(V& v)
{
// Declare iterator
typename V::iterator ptr;
for (ptr = v.begin(); ptr != v.end(); ptr++) {
cout << *ptr << ' ';
}
cout << '\n';
}
// Driver code
int main()
{
cout << "For Integer data_type" << endl;
GenericMyVector<int> v;
v.push_back(5);
v.push_back(6);
v.push_back(7);
v.push_back(8);
v.push_back(9);
v.push_back(10);
v.push_back(11);
v.push_back(12);
// Declare iterator for traversal in
// vector v
GenericMyVector<int>::iterator it;
// Function called to display element in
// vector in v
cout << "Element in vector v : ";
display_vector(v);
// Print the size of vector v
cout << "size: " << v.size() << endl;
// Print Element at index 2
cout << "v[2]: " << v[2] << '\n';
// Pop an element and print it
cout << "Popped Element: " << v.pop_back() << '\n';
display_vector(v);
cout << endl;
cout << "For Char data_type" << endl;
GenericMyVector<char> c;
c.push_back('a');
c.push_back('b');
c.push_back('c');
c.push_back('d');
c.push_back('e');
c.push_back('f');
c.push_back('g');
c.push_back('h');
// Declare iterator for traversal in
// vector c
GenericMyVector<char>::iterator it1;
// Function called to display element in
// vector in c
cout << "Element in vector c : ";
display_vector(c);
// Print the size of vector c
cout << "size: " << c.size() << '\n';
// Print Element at index 2
cout << "c[2]: " << c[2] << '\n';
// Pop an element and print it
cout << "pop: " << c.pop_back() << '\n';
// Function called to display element in
// vector in c
cout << "Element in vector c : ";
display_vector(c);
return 0;
}
Producción:
For Integer data_type Element in vector v : 5 6 7 8 9 10 11 12 size: 8 v[2]: 7 Popped Element: 12 5 6 7 8 9 10 11 For Char data_type Element in vector c : a b c d e f g h size: 8 c[2]: c pop: h Element in vector c : a b c d e f g