pointer/reference issues? ... newbie confused

crq · #1 22-Jan-2005, 22:56

i have been working on this all DAY LONG. i am new to C++ and Unix and need to write this little tiny code in both. i am tripping all over myself with references and dereferences and operator overloads .... if anyone could help me decipher what my problem(s) are, that would be a lifesaver right now.
this is the error that i keep getting ... and below is the code.

Code:

classroom(52)% g++ lab2aa.C
lab2aa.C: In function `int size()':
lab2aa.C:55: `d_num_elements' undeclared (first use this function)
lab2aa.C:55: (Each undeclared identifier is reported only once for each
function it appears in.)
lab2aa.C: At global scope:
lab2aa.C:59: syntax error before `&' token
lab2aa.C: In member function `void IntArray::init(const int*, int)':
lab2aa.C:82: no match for `IntArray& [int&]' operator
lab2aa.C:85: no match for `IntArray& [int&]' operator

CPP / C++ / C Code:

#include <iostream>
using namespace std;

#include "/unc/hedlund/121/lib/cpluslib.h"

class IntArray{


public:
        IntArray ( int sz = 10 );      
 
        IntArray ( const IntArray &x);

        virtual ~IntArray();

        int size () const;
    
        int &operator = ( int i ) const;

protected:
        int d_num_elements;
        int *d_array;


private:
        void init (const int *x, int sz);
};

IntArray::
IntArray  ( int sz )
{
        cout << "!!! default constructor called " <<endl;
        init ( NULL, sz);
}

IntArray::
IntArray ( const IntArray &x )
{
        cout<< "!!!  constructor" <<endl;
        init ( x.d_array, x.size() );
}

IntArray::
~IntArray()
{
        cout << "!!! IntArray destructor " <<endl;
        if ( size() > 0){
                delete [] d_array;
        }
}

int
size ()
{
        return (d_num_elements);
}

int IntArray::
&operator [] ( int i ) const
{
        return d_array[i];
}

void IntArray::
init ( const int *data, int sz)
{
        d_num_elements = sz;
        if ( 0 == d_num_elements ){                  // if no elements in array
                d_array = NULL;
        }
        else{
                d_array = new int [d_num_elements];
                                                     // allocate memory
                                                     // if new returns NULL then no
                                                     // more available memory
        }
        for (int i=0; i < sz; i++ ){
                                            // Loop Invariant:
                                            // for all j:0 .. i-1, self[j] == 0 OR
                                            //    self[j] == data[j]
                if ( NULL == data ){
                        self [i] = 0;
                }
                else{
                        self[i] = data[i];
                }
        }
}


int main () {
        IntArray a(5);
        IntArray b(8);
  cout << a.size() <<endl;
  cout << b.size() <<endl;
return(0); 
}

thanks for looking at this!!

crq

LuciWiz · #2 23-Jan-2005, 08:57

Quote:

Originally Posted by crq

CPP / C++ / C Code:

int IntArray::
&operator [] ( int i ) const
{
        return d_array[i];
}

This is wrong. You need to specify the return type before the resolution operator (:: ); the return type includes the reference operator (&):

CPP / C++ / C Code:

int & IntArray::
operator [] ( int i ) const
{
        return d_array[i];
}

I didn't follow all your code, so in case you have other errors, please let us know.

Kind regards,
Lucian

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Rate This Thread
Rate This Thread:

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Streamyx (DSL) and Windows ME issues.	JdS	Computer Software Forum - Windows	4	03-Apr-2004 05:15
Downloadable document compatibilty issues?	rhino1616	Web Design Forum	3	07-May-2003 04:05