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Hello,

I'd like to write a vector class using templates to be able to handle floats
and doubles.
I can't seem to find a way though to cast between the float type and the
double type
of the vector class. Is there a way of implementing the following
mini-example neatly ??

Thanks for any help,

Mike

//---------------------------------
template <class T>
class vector{
public:
T x,y;
vector(T xinit,T yinit){ x=xinit;y=yinit; }
void add(vector &v){
x += v.x;
y += v.y;
}
};

void main(){
vector <float> vector_float(2.0f,3.0f);
vector <float> vector2_float(2.0f,1.0f);
vector <double> vector_double(-1.0,3.0);

// this works of course:
vector_float.add(vector2_float);

// this throws a compile error: - how can something like this be achieved
?
vector_float.add(vector_double);
}


// the error thrown is:
/*
c:\coding\visc\mathtest\mathtest\main.cpp(26): error C2664: 'vector<T>::add'
: cannot convert parameter 1 from 'vector<T>' to 'vector<T> &'
with
[
T=float
]
and
[
T=double
]
and
[
T=float
]
*/

Mike Tyka wrote:
> I'd like to write a vector class using templates to be able to handle floats
> and doubles.
> I can't seem to find a way though to cast between the float type and the
> double type
> of the vector class. Is there a way of implementing the following
> mini-example neatly ??
>
> Thanks for any help,
>
> Mike
>
> //---------------------------------
> template <class T>
> class vector{
> public:
> T x,y;
> vector(T xinit,T yinit){ x=xinit;y=yinit; }
> void add(vector &v){
> x += v.x;
> y += v.y;
> }

Add this function:

template<class U> void add(vector<U> const &vu) {
x += vu.x;
y += vu.y;
}

The "native" 'add' will be used for the same type of vector, and the
templated 'add' will be used for "foreign" vectors.

> };
>
> void main(){

'main' _always_ returns an int.

> vector <float> vector_float(2.0f,3.0f);
> vector <float> vector2_float(2.0f,1.0f);
> vector <double> vector_double(-1.0,3.0);
>
> // this works of course:
> vector_float.add(vector2_float);
>
> // this throws a compile error: - how can something like this be achieved
> ?
> vector_float.add(vector_double);

You can define your 'add' as a template. See above.

> }
>
> [...]

Victor