Operator[ ]
Author
Heya,
say I have this class:
class matrix {
public:
float value[16];
matrix()
{
for(int j = 0; j < 16; j++)
value[j] = 0.0f;
}
};
I would like to define an operator[] that allows me to do stuff like this:
matrix M;
M[0] = 0;
M[1] = 1;
etc...
But I have no idea how to actually do this. Is it even possible?
Thanks
WickedMystic
Edited by - WickedMystic on 5/9/00 5:04:13 PM
Edited by - WickedMystic on 5/9/00 5:10:25 PM
The first operator[] is for read, the second is for read/write.
class CMatrix
{
public :
float operator[](unsigned int iElement) const { return m_afElements[iElement]; }
float& operator[](unsigned int iElement) { return m_afElements[iElement]; }
private :
float m_afElements[16];
};
class CMatrix
{
public :
float operator[](unsigned int iElement) const { return m_afElements[iElement]; }
float& operator[](unsigned int iElement) { return m_afElements[iElement]; }
private :
float m_afElements[16];
};
Hate to tell you this, but i don't think it can be done with that type of symbol.
M[] is used for arrays, such as you had made Matrix M[20]; so I think you would have to do something different.
You could make a function :
Matrix::setcell(int cell, float toset)
{
value[cell]=toset;
}
I think that should work... I might be wrong about not being able to do it your way, but I really don't think it would work.
Drakonite
--Don't quote me on that, unless I'm right.
Edited by - Drakonite on May 9, 2000 6:19:17 PM
M[] is used for arrays, such as you had made Matrix M[20]; so I think you would have to do something different.
You could make a function :
Matrix::setcell(int cell, float toset)
{
value[cell]=toset;
}
I think that should work... I might be wrong about not being able to do it your way, but I really don't think it would work.
Drakonite
--Don't quote me on that, unless I'm right.
Edited by - Drakonite on May 9, 2000 6:19:17 PM
So you want to do something like this:
class Array {
char A[256];
public:
char operator[](int index);
};
char Array::operator[](int index) {
return A[index];
}
class Array {
char A[256];
public:
char operator[](int index);
};
char Array::operator[](int index) {
return A[index];
}
Oh I see what you want it to do now 
. You''ll have to pass it back as a reference. Code below...
class CArray {
int Array[256];
public:
CArray();
int& operator[](int index);
};
CArray::CArray()
{
for(int x = 0; x < 256; x++)
Array[x] = 0;
}
int& CArray::operator[](int index)
{
return Array[index];
}
That will do what you want it to.
. You''ll have to pass it back as a reference. Code below...class CArray {
int Array[256];
public:
CArray();
int& operator[](int index);
};
CArray::CArray()
{
for(int x = 0; x < 256; x++)
Array[x] = 0;
}
int& CArray::operator[](int index)
{
return Array[index];
}
That will do what you want it to.
You might want to make the const version of operator[] return a const reference.
as in
const float& operator[](unsigned int index) const;
as in
const float& operator[](unsigned int index) const;
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