I need to have a constructor that is passed a integer number that defines
the size of an array in the private area of the Class. Is that possible?
For example in main() the user is asked for the number of lanes. Then when
the object is declared after that it is passed that integer, which then
creates an array of pointers.
14  4347 
- Steve - wrote: I need to have a constructor that is passed a integer number that defines
the size of an array in the private area of the Class. Is that possible?
For example in main() the user is asked for the number of lanes. Then when
the object is declared after that it is passed that integer, which then
creates an array of pointers.
you could use a std::vector
i.e.
class Lanes
{
std::vector< Lane * > m_lane_array;
public:
Lanes( int size )
: m_lane_array( size )
{
}
};
"- Steve -" <se****@foundat ion.sdsu.edu> wrote in message
news:k8******** *********@news2 .central.cox.ne t... I need to have a constructor that is passed a integer number that defines
the size of an array in the private area of the Class. Is that possible?
Yes, constructors can take parameters like normal functions. Use an
std::vector in your private area and call .resize() in your constructor to
set the array size. In fact you don't even need to resize it, as it'll grow
as data is added. Get hold of an elementary C++ reference to learn more.
vectors are fine if you like std, personally i use std sparingly
all ya have to do is use new
Object *_array = new Objects[t];
or
typedef Object *PObject;
Object **_array = new PObject[t];
depending on what exactly your looking to do
"- Steve -" <se****@foundat ion.sdsu.edu> wrote in message
news:k8******** *********@news2 .central.cox.ne t... I need to have a constructor that is passed a integer number that defines
the size of an array in the private area of the Class. Is that possible?
For example in main() the user is asked for the number of lanes. Then
when the object is declared after that it is passed that integer, which then
creates an array of pointers.
"- Steve -" <se****@foundat ion.sdsu.edu> wrote in message
news:k8******** *********@news2 .central.cox.ne t... I need to have a constructor that is passed a integer number that defines
the size of an array in the private area of the Class. Is that possible?
For example in main() the user is asked for the number of lanes. Then
when the object is declared after that it is passed that integer, which then
creates an array of pointers.
You should declare your constructor to be explicit because the parameter
passed to the
constructor determines the object's configuration. This way you prevent any
implicit
conversions that may otherwise occur inadvertently.
With best wishes,
J.Schafer
"TR" <no@spam.com> wrote in message
news:R_******** *********@news-binary.blueyond er.co.uk... "- Steve -" <se****@foundat ion.sdsu.edu> wrote in message
news:k8******** *********@news2 .central.cox.ne t... I need to have a constructor that is passed a integer number that
defines the size of an array in the private area of the Class. Is that
possible?
Yes, constructors can take parameters like normal functions. Use an
std::vector in your private area and call .resize() in your constructor to
set the array size. In fact you don't even need to resize it, as it'll
grow as data is added. Get hold of an elementary C++ reference to learn more.
Err, you can't resize an array. I think you are thinking of a vector.
john
"- Steve -" <se****@foundat ion.sdsu.edu> wrote in message
news:k8******** *********@news2 .central.cox.ne t... I need to have a constructor that is passed a integer number that defines
the size of an array in the private area of the Class. Is that possible?
For example in main() the user is asked for the number of lanes. Then
when the object is declared after that it is passed that integer, which then
creates an array of pointers.
Don't use an array, use a vector. Something like this
#include <vector>
class LaneVector
{
public:
LaneVector(int num_lanes) : lanes(num_lanes )
{
}
private:
std::vector<Lan e> lanes;
};
You should really learn about vectors, make your life much easier.
john
dwrayment wrote:
vectors are fine if you like std, personally i use std sparingly
all ya have to do is use new
Object *_array = new Objects[t];
.... and by thus have opened the 'Hey why use something
simple when there is a more complicate way' season.
By doing the memory management by yourself, your class
suddenly also needs: a destructor, an assignment operator,
a copy constructor. And all of them have, of course, to be
written correctly!
So why would you want to do this, when vector is available
and saves you from all this possible pitfalls?
--
Karl Heinz Buchegger kb******@gascad .at
John Harrison wrote:
"TR" <no@spam.com> wrote in message
news:R_******** *********@news-binary.blueyond er.co.uk... "- Steve -" <se****@foundat ion.sdsu.edu> wrote in message
news:k8******** *********@news2 .central.cox.ne t... > I need to have a constructor that is passed a integer number that defines > the size of an array in the private area of the Class. Is that
possible?
Yes, constructors can take parameters like normal functions. Use an
std::vector in your private area and call .resize() in your constructor
to set the array size. In fact you don't even need to resize it, as it'll
grow as data is added. Get hold of an elementary C++ reference to learn more.
Err, you can't resize an array. I think you are thinking of a vector.
john
That's why s/he said quite clearly "Use an STD::vector..." .
pete
"Peter Gregory" <pe***********@ durham.ac.uk> wrote in message
news:be******** **@sirius.dur.a c.uk... John Harrison wrote:
"TR" <no@spam.com> wrote in message
news:R_******** *********@news-binary.blueyond er.co.uk... "- Steve -" <se****@foundat ion.sdsu.edu> wrote in message
news:k8******** *********@news2 .central.cox.ne t...
> I need to have a constructor that is passed a integer number that
defines > the size of an array in the private area of the Class. Is that
possible?
Yes, constructors can take parameters like normal functions. Use an
std::vector in your private area and call .resize() in your constructor
to set the array size. In fact you don't even need to resize it, as
it'll grow as data is added. Get hold of an elementary C++ reference to learn
more.
Err, you can't resize an array. I think you are thinking of a vector.
john
That's why s/he said quite clearly "Use an STD::vector..." .
pete
Hmm, shortly followed by "call .resize() in your constructor to set the
array size", but maybe I should learn to read.
Also the statement "In fact you don't even need to resize it, as it'll grow
as data is added." is misleading at best.
john This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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