Re: template class

[eric <fsshl at att dot net>]

Dear Mr. Bjarne Stroustrup:

  Thanks your suggestion, I follow it but it show fatal error:Array.cpp:
no such file
so
I add #include "Array.cpp" in my main program, pg52.cpp
then
it can compile
but
when I run it, it response
Segmentation fault

again it's g++ 4.5.2.  What may cause wrong?

hope to see your suggestion/advice again, and thanks a lot in advance,
Eric
-----------------------------------------------------

On Fri, 2011-06-10 at 22:18 -0400, bs wrote:
> On 6/10/2011 9:43 PM, eric wrote:
> > Dear Bjarne Stroustrup:
> >
> >    I copied a piece of codes from book(C++ primer 3rd Ed) chapter 2 about
> > page 52.
> > but it failed to be compiled under my g++ 4.5.2
> > here is the program
> 
> That book is an antique, but I think that the problem may simply be that 
> you can't separately compile pg52.cpp and Array.cpp. Try 
> #include<Array.cpp> in Array.h .
> 
> > -----------------------
> >
> > eric@eric-laptop:~/CppPrimer3$ g++ Array.cpp pg52.cpp
> > /tmp/ccE9MPMg.o: In function `main':
> > pg52.cpp:(.text+0x23): undefined reference to `Array<int>::Array(int)'
> > pg52.cpp:(.text+0x37): undefined reference to
> > `Array<double>::Array(int)'
> > pg52.cpp:(.text+0x4b): undefined reference to `Array<char>::Array(int)'
> > collect2: ld returned 1 exit status
> > --------------------------------------------------
> > #include<iostream>
> > #include "Array.h"
> >
> >
> >
> > int main() {
> >    const int array_size = 4;
> >
> >    // elemType becomes int
> >    Array<int>  ia(array_size);
> >
> >    // elemType becomes double
> >    Array<double>  da(array_size);
> >
> >    // elemType becomes char
> >    Array<char>  ca(array_size);
> >
> >     int ix;
> >
> >     for ( ix = 0; ix<  array_size; ++ix ) {
> >           ia[ix] = ix;
> >           da[ix] = ix * 1.75;
> >           ca[ix] = ix + 'a';
> >      }
> >
> >      for ( ix = 0; ix<  array_size; ++ix )
> >            std::cout<<  "[ "<<  ix<<  " ]   ia: "<<  ia[ix]
> >                 <<  "\tca: "<<  ca[ix]
> >                 <<  "\tda: "<<  da[ix]<<  std::endl;
> >
> >   return 0;
> > }
> > -------------------
> > // Array.cpp
> >
> > #include "Array.h"
> >
> > /*
> > Array::Array(elemType *iarray, int iarray_size)
> > {
> >    ia = iarray;
> >    _size = iarray_size;
> > }
> > */
> >
> > template<class T>  Array<T>::Array(const Array<T>  &rhs )
> > {
> >    ia = rhs;
> > }
> >
> > template<class T>  Array<T>::Array(const int size )
> > {
> >    _size = size;
> > }
> >
> >
> > ------------------------------------------------------
> > #ifndef Array_H
> > #define Array_H
> >
> >
> > template<  class elemType>
> > class Array {
> > public:
> >    // parameterize element type
> >    explicit Array( int size = DefaultArraySize );
> >    Array( elemType *array, int array_size );
> >    Array( const Array&rhs );
> >
> >    virtual ~Array() { delete [] ia; }
> >
> >    bool operator==( const Array&  ) const;
> >    bool operator!=( const Array&  ) const;
> >
> >    Array&  operator=( const Array&  );
> >    int size() const { return _size; }
> >
> >    /* virtual */ elemType&  operator[](int index){ return ia[index]; }
> >    /*
> >    virtual void sort();
> >
> >    virtual elemType min() const;
> >    virtual elemType max() const; */
> >    /* virtual */ int      find( const elemType&value ) const;
> >
> > protected:
> >     static const int DefaultArraySize = 12;
> >
> >     int _size;
> >     elemType *ia;
> > };
> >
> > #endif
> > ---------------------------------------------------------------
> > I asked mailing list in gcc, but so far I did not get any useful
> > response.  I know the book's author Stanley B. Lippman or Josee Lajoie
> > ever work with you.  And I tried to reach Stanley B. Lippman, I can not
> > find his email addreess.  I emailed Josee Lajoie but again never get any
> > message from her (for 2 or 3 days).
> > hope to get your help on this problem.
> > Thanks your efforts a lot in advance
> > Eric
> >
> >
>