104. Vector

class Number
{
private:
    int val;
public:
    Number() : val(0) { }
    Number(int val) : val(val) { }

    operator int(){ return val; }
};

template <typename T> class Vector
{
private:
    T* data;
    unsigned int dataCapacity, dataSize;
public:
    Vector()
        :dataCapacity(2), dataSize(0)
    {
        this->data = new T[2];
    }
    ~Vector()
    {
        delete[] this->data;
    }
    unsigned int size() { return dataSize; }
    unsigned int capacity() { return dataCapacity; }

    void resize(unsigned int newSize)
    {
        T* newMem = new T[newSize];
        dataSize = (dataSize>newSize ? newSize : dataSize);
        dataCapacity = newSize;

        for (unsigned int i = 0; i < dataSize ; ++i)         
        {
            newMem[i] = this->data[i];
        }

        delete[] this->data;
        this->data = newMem;
    }

    void push_back(T& newData)
    {
        if (dataSize + 1 > dataCapacity)
        {
            resize(dataCapacity * 2);
        }

        this->data[dataSize] = newData;
        ++dataSize;
    }

    void pop_back()
    {
        if (dataSize >0)
            --dataSize;
    }

    T& operator[] (unsigned int subscript)
    {
        return data[subscript];
    }
};

int main(int argc, char** argv)
{
    Vector<Number> dataVector;

    dataVector.push_back(Number(1));
    dataVector.push_back(Number(3));
    dataVector.push_back(Number(6));

    for (unsigned int i = 0; i < dataVector.size(); ++i)
    {
        printf("%d\n", (int)(dataVector[i]));
    }
    printf("Size : %d Capacity %d \n",
        dataVector.size(), dataVector.capacity() );

    dataVector.pop_back();
    for (unsigned int i = 0; i < dataVector.size(); ++i)
    {
        printf("%d\n", (int)(dataVector[i]));
    }
    printf("Size : %d Capacity %d \n",
        dataVector.size(), dataVector.capacity());

    dataVector.resize(1);
    for (unsigned int i = 0; i < dataVector.size(); ++i)
    {
        printf("%d\n", (int)(dataVector[i]));
    }
    printf("Size : %d Capacity %d \n",
        dataVector.size(), dataVector.capacity());
}

1
3
6
Size : 3 Capacity 4
1
3
Size : 2 Capacity 4
1
Size : 1 Capacity 1

#include <iostream>
#include <vector>

class Number
{
private:
    int val;
public:
    Number() : val(0) { }
    Number(int val) : val(val) { }

    operator int(){ return val; }
};

int main(int argc, char** argv)
{
    std::vector<Number> dataVector;

    dataVector.push_back(Number(1));
    dataVector.push_back(Number(3));
    dataVector.push_back(Number(6));

    // by index value
    for (auto i = 0; i < dataVector.size(); i++)
    {
        printf("%d\n", (int)(dataVector[i]));
    }
    printf("Size : %d Capacity %d \n",
        dataVector.size(), dataVector.capacity());

    dataVector.pop_back();
    // by iterator
    for (auto iter = dataVector.begin();
        iter != dataVector.end(); iter++)
    {
        printf("%d\n", (int)(*iter));
    }
    printf("Size : %d Capacity %d \n",
        dataVector.size(), dataVector.capacity());

    dataVector.resize(1);
    // by range-based for loops
    for (Number& iter : dataVector)
    {
        printf("%d\n", (int)(iter));
    }
    printf("Size : %d Capacity %d \n",
        dataVector.size(), dataVector.capacity());
}

1
3
6
Size : 3 Capacity 3
1
3
Size : 2 Capacity 3
1
Size : 1 Capacity 3