IntArray

#include <iostream>

using namespace std;

class intArray
{
    private:
        int size, capacity, *a;
    public:
        intArray(int n = 0, int val = 0);
        intArray(const intArray &);
        ~intArray();
        void push_back(int val);
        intArray & operator = (const intArray &);
};

intArray::intArray(int n, int val)
{
    a = nullptr;
    capacity = size = 0;

    if(n > 0){
        a = new int[n];
        capacity = size = n;
        for(int i = 0; i < size; ++i)
            a[i] = val;
    }
}

intArray::intArray(const intArray & src)
{
    a = nullptr;
    capacity = size = 0;

    if(src.size > 0){
        a = new int[src.size];
        capacity = size = src.size;
        for(int i = 0; i < size; ++i)
            a[i] = src.a[i];
    }
}

intArray::~intArray()
{
    if(capacity > 0)
        delete [] a;
}

intArray & intArray::operator = (const intArray & src)
{
    if(capacity < src.capacity){
        if(capacity > 0)
            delete [] a;
        a = new int[src.capacity];
        capacity = src.size;
    }
    size = src.size;
    for(int i = 0; i < size; ++i)
        a[i] = src.a[i];
}

void intArray::push_back(int val)
{
    if(size == capacity)
    {
        int new_capacity = capacity > 0 ? 2 * capacity : 1;
        int * new_a = new int[new_capacity];
        for(int i = 0; i < size; ++i)
            new_a[i] = a[i];
        delete [] a;
        a = new_a;
        capacity = new_capacity;
    }
    a[size++] = val;
}