* [C++] Derive a class from a tamplate
@ 2005-07-31 17:49 stefano luceri
2005-07-31 18:23 ` corey taylor
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: stefano luceri @ 2005-07-31 17:49 UTC (permalink / raw)
To: gcc-help
Hello to all .... excuse for my bad english
I've the following problem writing a simple program. I would use the
metods of std::valarray class adding some self writed method for elemnts
of double type.
I've thought something like this:
/****************************/
using namespace std;
class mvector : public valarray<double>
{
mvector();
mvector(int size);
}
mvector :: mvector() : valarray<double>() {}
mvector :: mvector(int size) : valarray<double>(size) {}
int main()
{
mvector v(3);
v = (v+2.0);
}
/*****************************/
Compiling this code I obtain the following error:
geom.cpp: In function `int main()':
geom.cpp:38: error: no match for 'operator=' in 'v = std::operator+(const
std::valarray<_Tp>&, const _Tp&) [with _Tp = double]((&1.0e+0))'
geom.cpp:22: error: candidates are: mvector& mvector::operator=(const
mvector&)
make: *** [geom.o] Error 1
Why can't I use the operator = like I do with valarray?
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [C++] Derive a class from a tamplate
2005-07-31 17:49 [C++] Derive a class from a tamplate stefano luceri
@ 2005-07-31 18:23 ` corey taylor
2005-07-31 18:35 ` Nusret BALCI
2005-07-31 20:04 ` Nusret BALCI
2005-08-01 14:34 ` random
2 siblings, 1 reply; 5+ messages in thread
From: corey taylor @ 2005-07-31 18:23 UTC (permalink / raw)
To: stefano luceri; +Cc: gcc-help
stefano,
After taking a quick look at valarray, it seems that operator
overloads that declare operator+ for valarray are non-member
functions.
You will need to declarea set of operator+ overloads for mvector in
the same style as valarray overloads. I think this is the problem
you're seeing.
Is there a reason you're trying to force a copy with the code above?
corey
On 7/31/05, stefano luceri <stefano@communicationfactory.it> wrote:
> Hello to all .... excuse for my bad english
>
> I've the following problem writing a simple program. I would use the
> metods of std::valarray class adding some self writed method for elemnts
> of double type.
>
> I've thought something like this:
>
> /****************************/
> using namespace std;
>
> class mvector : public valarray<double>
> {
> mvector();
> mvector(int size);
> }
>
> mvector :: mvector() : valarray<double>() {}
> mvector :: mvector(int size) : valarray<double>(size) {}
>
> int main()
> {
> mvector v(3);
>
> v = (v+2.0);
> }
>
> /*****************************/
>
> Compiling this code I obtain the following error:
>
> geom.cpp: In function `int main()':
> geom.cpp:38: error: no match for 'operator=' in 'v = std::operator+(const
> std::valarray<_Tp>&, const _Tp&) [with _Tp = double]((&1.0e+0))'
> geom.cpp:22: error: candidates are: mvector& mvector::operator=(const
> mvector&)
> make: *** [geom.o] Error 1
>
> Why can't I use the operator = like I do with valarray?
>
>
>
>
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [C++] Derive a class from a tamplate
2005-07-31 18:23 ` corey taylor
@ 2005-07-31 18:35 ` Nusret BALCI
0 siblings, 0 replies; 5+ messages in thread
From: Nusret BALCI @ 2005-07-31 18:35 UTC (permalink / raw)
To: corey taylor; +Cc: gcc-help
[-- Attachment #1: Type: text/plain, Size: 1893 bytes --]
Stefano,
Does this work for you? (see the attached file).
Nusret
--- corey taylor <corey.taylor@gmail.com> wrote:
> stefano,
>
> After taking a quick look at valarray, it seems
> that operator
> overloads that declare operator+ for valarray are
> non-member
> functions.
>
> You will need to declarea set of operator+
> overloads for mvector in
> the same style as valarray overloads. I think this
> is the problem
> you're seeing.
>
> Is there a reason you're trying to force a copy
> with the code above?
>
> corey
>
> On 7/31/05, stefano luceri
> <stefano@communicationfactory.it> wrote:
> > Hello to all .... excuse for my bad english
> >
> > I've the following problem writing a simple
> program. I would use the
> > metods of std::valarray class adding some self
> writed method for elemnts
> > of double type.
> >
> > I've thought something like this:
> >
> > /****************************/
> > using namespace std;
> >
> > class mvector : public valarray<double>
> > {
> > mvector();
> > mvector(int size);
> > }
> >
> > mvector :: mvector() : valarray<double>() {}
> > mvector :: mvector(int size) :
> valarray<double>(size) {}
> >
> > int main()
> > {
> > mvector v(3);
> >
> > v = (v+2.0);
> > }
> >
> > /*****************************/
> >
> > Compiling this code I obtain the following error:
> >
> > geom.cpp: In function `int main()':
> > geom.cpp:38: error: no match for 'operator=' in 'v
> = std::operator+(const
> > std::valarray<_Tp>&, const _Tp&) [with _Tp =
> double]((&1.0e+0))'
> > geom.cpp:22: error: candidates are: mvector&
> mvector::operator=(const
> > mvector&)
> > make: *** [geom.o] Error 1
> >
> > Why can't I use the operator = like I do with
> valarray?
> >
> >
> >
> >
> >
> >
>
____________________________________________________
Start your day with Yahoo! - make it your home page
http://www.yahoo.com/r/hs
[-- Attachment #2: 3181431787-a.cpp --]
[-- Type: text/plain, Size: 463 bytes --]
/****************************/
#include<valarray>
using namespace std;
class mvector : public valarray<double>
{
public:
mvector();
mvector(int size);
mvector& operator=(valarray<double>& arg){
return (mvector&)(this/*maybe not necessary*/->valarray<double>::operator=(arg));
}
};
mvector::mvector() : valarray<double>() {}
mvector::mvector(int size): valarray<double>(size){}
int main()
{
mvector v(3);
v = (mvector&)((valarray<double>&)v + 2.0);
}
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [C++] Derive a class from a tamplate
2005-07-31 17:49 [C++] Derive a class from a tamplate stefano luceri
2005-07-31 18:23 ` corey taylor
@ 2005-07-31 20:04 ` Nusret BALCI
2005-08-01 14:34 ` random
2 siblings, 0 replies; 5+ messages in thread
From: Nusret BALCI @ 2005-07-31 20:04 UTC (permalink / raw)
To: stefano luceri; +Cc: gcc-help
[-- Attachment #1: Type: text/plain, Size: 1388 bytes --]
Hey,
it seems that only one single cast is enough. Sorry,
I'm not a professional programmer: this seems to work
fine though..
--- stefano luceri <stefano@communicationfactory.it>
wrote:
> Hello to all .... excuse for my bad english
>
> I've the following problem writing a simple program.
> I would use the
> metods of std::valarray class adding some self
> writed method for elemnts
> of double type.
>
> I've thought something like this:
>
> /****************************/
> using namespace std;
>
> class mvector : public valarray<double>
> {
> mvector();
> mvector(int size);
> }
>
> mvector :: mvector() : valarray<double>() {}
> mvector :: mvector(int size) :
> valarray<double>(size) {}
>
> int main()
> {
> mvector v(3);
>
> v = (v+2.0);
> }
>
> /*****************************/
>
> Compiling this code I obtain the following error:
>
> geom.cpp: In function `int main()':
> geom.cpp:38: error: no match for 'operator=' in 'v =
> std::operator+(const
> std::valarray<_Tp>&, const _Tp&) [with _Tp =
> double]((&1.0e+0))'
> geom.cpp:22: error: candidates are: mvector&
> mvector::operator=(const
> mvector&)
> make: *** [geom.o] Error 1
>
> Why can't I use the operator = like I do with
> valarray?
>
>
>
>
>
>
____________________________________________________
Start your day with Yahoo! - make it your home page
http://www.yahoo.com/r/hs
[-- Attachment #2: 3181431787-a.cpp --]
[-- Type: text/plain, Size: 315 bytes --]
/****************************/
#include<valarray>
using namespace std;
class mvector : public valarray<double>
{
public:
mvector();
mvector(int size);
};
mvector::mvector() : valarray<double>() {}
mvector::mvector(int size): valarray<double>(size){}
int main()
{
mvector v(3);
v = (mvector&)(v + 2.0);
}
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [C++] Derive a class from a tamplate
2005-07-31 17:49 [C++] Derive a class from a tamplate stefano luceri
2005-07-31 18:23 ` corey taylor
2005-07-31 20:04 ` Nusret BALCI
@ 2005-08-01 14:34 ` random
2 siblings, 0 replies; 5+ messages in thread
From: random @ 2005-08-01 14:34 UTC (permalink / raw)
To: stefano luceri; +Cc: gcc-help
stefano luceri wrote:
> Hello to all .... excuse for my bad english
>
> I've the following problem writing a simple program. I would use the
> metods of std::valarray class adding some self writed method for
> elemnts of double type.
>
I would be very careful about overriding valarray unless you know what
you are doing, it uses some very strange implementation techniques.
Couldn't you use vector instead? or a member of type valarray? Or do you
need/want to extra features valarray offers?
^ permalink raw reply [flat|nested] 5+ messages in thread
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2005-07-31 17:49 [C++] Derive a class from a tamplate stefano luceri
2005-07-31 18:23 ` corey taylor
2005-07-31 18:35 ` Nusret BALCI
2005-07-31 20:04 ` Nusret BALCI
2005-08-01 14:34 ` random
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