gridptr.h

C++高级编程这本书所附的源代码

#include "Grid.h"

template <typename T>
class Grid<T*>
{
    public:
        Grid(int inWidth = kDefaultWidth, int inHeight = kDefaultHeight);
        Grid(const Grid<T*>& src);
        ~Grid();
        Grid<T*>& operator=(const Grid<T*>& rhs);

        void setElementAt(int x, int y, const T* inElem);
        T* getElementAt(int x, int y) const;
        int getHeight() const { return mHeight; }
        int getWidth() const { return mWidth; }
        static const int kDefaultWidth = 10;
        static const int kDefaultHeight = 10;
    protected:
        void copyFrom(const Grid<T*>& src);
        T** mCells;
        int mWidth, mHeight;
}; 

template <typename T>
const int Grid<T*>::kDefaultWidth;

template <typename T>
const int Grid<T*>::kDefaultHeight;

template <typename T>
Grid<T*>::Grid(int inWidth, int inHeight) : mWidth(inWidth), mHeight(inHeight)
{
  mCells = new T* [mWidth];
  for (int i = 0; i < mWidth; i++) {
    mCells[i] = new T[mHeight];
  }
}

template <typename T>
Grid<T*>::Grid(const Grid<T*>& src)
{
    copyFrom(src);
}

template <typename T>
Grid<T*>::~Grid()
{
    // free the old memory
    for (int i = 0; i < mWidth; i++) {
        delete [] mCells[i];
    }
    delete [] mCells;
}

template <typename T>
void Grid<T*>::copyFrom(const Grid<T*>& src)
{
    int i, j;
    mWidth = src.mWidth;
    mHeight = src.mHeight;

    mCells = new T* [mWidth];
    for (i = 0; i < mWidth; i++) {
        mCells[i] = new T[mHeight];
    }

    for (i = 0; i < mWidth; i++) {
        for (j = 0; j < mHeight; j++) {
            mCells[i][j] = src.mCells[i][j];
        }
    }
}

template <typename T>
Grid<T*>& Grid<T*>::operator=(const Grid<T*>& rhs)
{
    // check for self-assignment
    if (this == &rhs) {
        return (*this);
    }
    // free the old memory
    for (int i = 0; i < mWidth; i++) {
        delete [] mCells[i];
    }
    delete [] mCells;

    // copy the new memory
    copyFrom(rhs);
    return (*this);
}

template <typename T>
void Grid<T*>::setElementAt(int x, int y, const T* inElem)
{
    mCells[x][y] = *inElem;
}

template <typename T>
T* Grid<T*>::getElementAt(int x, int y) const
{
    T* newElem = new T(mCells[x][y]);
    return (newElem);
}