I want to compose a Matrix class template.
Matrix objects need to copy data very often, such as in copy constructor or assignment operator overload function, so it need to be efficient.
For most cases, I should not escape the assignment operator overload function of each data item, but for simple data types, I prefer using memcpy() to speed it up.
So I write like this:
#ifndef GRAPHIC_VECTOR_H
#define GRAPHIC_VECTOR_H
namespace Graphic
{
template <typename T>
class Matrix
{
private:
unsigned row, col;
T* data;
void CopyData(T* dest, T* src, unsigned count);
public:
Matrix(unsigned row, unsigned col, T* data, int count = -1) : row(row), col(col)
{
this->data = new T[row * col];
CopyData(this->data, data, (count > 0 ? count : row * col * sizeof(T)));
}
~Matrix()
{
delete[] this->data;
}
};
template <typename T>
void Matrix<T>::CopyData(T* dest, T* src, unsigned count)
{
int i;
for (i = 0; i < count; i++)
{
dest[i] = src[i];
}
}
template <>
void Matrix<double>::CopyData(double* dest, double* src, unsigned count)
{
memcpy(dest, src, count);
}
template <>
void Matrix<float>::CopyData(float* dest, float* src, unsigned count)
{
memcpy(dest, src, count);
}
template <>
void Matrix<int>::CopyData(int* dest, int* src, unsigned count)
{
memcpy(dest, src, count);
}
template <>
void Matrix<unsigned>::CopyData(unsigned* dest, unsigned* src, unsigned count)
{
memcpy(dest, src, count);
}
}
#endifThen I do this in the main function:
double data[9] = {1,2,3,4,5,6,7,8,9};
Graphic::Matrix<double> m(3,3,data);Compilation is a great success but I got some link errors:
Linking...
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\controller.o(.text+0x0): In function `ZN7Graphic6MatrixIdE8CopyDataEPdS2_j':
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\graphic\matrix.h:37: multiple definition of `Graphic::Matrix<double>::CopyData(double*, double*, unsigned)'
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\winmain.o(.text+0x0):C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\winmain.cpp: first defined here
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\controller.o(.text+0x22): In function `ZN7Graphic6MatrixIfE8CopyDataEPfS2_j':
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\graphic\matrix.h:43: multiple definition of `Graphic::Matrix<float>::CopyData(float*, float*, unsigned)'
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\winmain.o(.text+0x22):C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\graphic\matrix.h:43: first defined here
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\controller.o(.text+0x44): In function `ZN7Graphic6MatrixIiE8CopyDataEPiS2_j':
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\graphic\matrix.h:49: multiple definition of `Graphic::Matrix<int>::CopyData(int*, int*, unsigned)'
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\winmain.o(.text+0x44):C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\graphic\matrix.h:49: first defined here
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\controller.o(.text+0x66): In function `ZN7Graphic6MatrixIjE8CopyDataEPjS2_j':
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\graphic\matrix.h:55: multiple definition of `Graphic::Matrix<unsigned>::CopyData(unsigned*, unsigned*, unsigned)'
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\winmain.o(.text+0x66):C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\graphic\matrix.h:55: first defined here
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\graphic.o(.text+0x0): In function `ZN7Graphic6MatrixIdE8CopyDataEPdS2_j':
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\graphic\matrix.h:37: multiple definition of `Graphic::Matrix<double>::CopyData(double*, double*, unsigned)'
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\winmain.o(.text+0x0):C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\winmain.cpp: first defined here
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\graphic.o(.text+0x22): In function `ZN7Graphic6MatrixIfE8CopyDataEPfS2_j':
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\graphic\matrix.h:43: multiple definition of `Graphic::Matrix<float>::CopyData(float*, float*, unsigned)'
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\winmain.o(.text+0x22):C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\graphic\matrix.h:43: first defined here
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\graphic.o(.text+0x44): In function `ZN7Graphic6MatrixIiE8CopyDataEPiS2_j':
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\graphic\matrix.h:49: multiple definition of `Graphic::Matrix<int>::CopyData(int*, int*, unsigned)'
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\winmain.o(.text+0x44):C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\graphic\matrix.h:49: first defined here
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\graphic.o(.text+0x66): In function `ZN7Graphic6MatrixIjE8CopyDataEPjS2_j':
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\graphic\matrix.h:55: multiple definition of `Graphic::Matrix<unsigned>::CopyData(unsigned*, unsigned*, unsigned)'
C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\Debug\winmain.o(.text+0x66):C:\Users\deltamaster\Documents\MinGWProject\graphic\3d\graphic\matrix.h:55: first defined here
