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help with dynamic memory

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Join Date: Sep 2004

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Narue

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Re: help with dynamic memory

#11

May 14th, 2007

>you are trying to access a private member with your object in the main function.
No, he's not. He's trying to access a private member of an object from within a public member function of the same class. Note the function definition:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
void Names::enter_new()
void Names::enter_new()

Unless the rules have recently changed without my knowing, that's not a correct definition of main. The access is legal.

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Narue

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Re: help with dynamic memory

#12

May 14th, 2007

Here's an example of what I mean, m3an, since words don't seem to have sufficient effect. I've corrected your errors and added enough to "use dynamic memory and classes together":

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
#include <string>
#include <new>
 
using namespace std;
 
class Names { 
private: 
  string title;
  string *p;
  int i;
public:
  Names ( const string& init ): title ( init ) {}
  ~Names() { delete[] p; }
  void enter_new();
  void display();
}; 
 
void Names::enter_new()
{
  cout<<"How many movies would you like to type? ";
  cin>> i;
  cin.ignore();
 
  p = new(nothrow) string[i];
 
  if ( p == 0 )
    cout << "Error: memory could not be allocated";
  else {
    for ( int a = 0; a < i; a++ ) {
      cout<<"Actor "<< a + 1 <<": "; 
      getline ( cin, p[a] );
    }
  }
}
 
void Names::display()
{
  cout<<"Title: "<< title <<"\nActors:\n";
 
  for ( int a = 0; a < i; a++ )
    cout<<'\t'<< p[a] <<'\n';
}
 
int main()
{
  Names film ( "My film" );
 
  film.enter_new();
  film.display();
}
#include <iostream>
#include <string>
#include <new>

using namespace std;

class Names { 
private: 
  string title;
  string *p;
  int i;
public:
  Names ( const string& init ): title ( init ) {}
  ~Names() { delete[] p; }
  void enter_new();
  void display();
}; 

void Names::enter_new()
{
  cout<<"How many movies would you like to type? ";
  cin>> i;
  cin.ignore();

  p = new(nothrow) string[i];

  if ( p == 0 )
    cout << "Error: memory could not be allocated";
  else {
    for ( int a = 0; a < i; a++ ) {
      cout<<"Actor "<< a + 1 <<": "; 
      getline ( cin, p[a] );
    }
  }
}

void Names::display()
{
  cout<<"Title: "<< title <<"\nActors:\n";

  for ( int a = 0; a < i; a++ )
    cout<<'\t'<< p[a] <<'\n';
}

int main()
{
  Names film ( "My film" );

  film.enter_new();
  film.display();
}

Have I still not answered your question?

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desijays

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Re: help with dynamic memory

#13

May 14th, 2007

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Originally Posted by m3an

its part of a dvd program. i want all the objects created and manipulated by the program to be stored in a dynamic array that might grow during the execution of the program. I want to program to store the info in a dynamic array that i can call anywhere to list the info.im having trouble with using dynamic memory and classes together, ...please help, thanks

Help with Code Tags C++ Syntax (Toggle Plain Text) class Names { private: string title; int i; int * p; public: void enter_new(); // sets names of actors to the DVD }film; void Names::enter_new() {char ans; cout << "How many movies would you like to type? "; cin >> film.i; //I was talking about this Narua int ii= film.i; (film.p)= new int[ii]; if ((film.p) == 0) cout << "Error: memory could not be allocated"; else { for (int a=1; a<(ii); a++) {cout<<"\n Please enter the name: "<<endl; cin >> (film.p)[a]; } delete[] p; } class Names { private: string title; int i; int * p; public: void enter_new(); // sets names of actors to the DVD }film; void Names::enter_new() {char ans; cout << "How many movies would you like to type? "; cin >> film.i; //I was talking about this Narua int ii= film.i; (film.p)= new int[ii]; if ((film.p) == 0) cout << "Error: memory could not be allocated"; else { for (int a=1; a<(ii); a++) {cout<<"\n Please enter the name: "<<endl; cin >> (film.p)[a]; } delete[] p; }

Were you referring to something else mate?

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m3an

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Re: help with dynamic memory

#14

May 14th, 2007

>I guess I'm not smart enough. Please point out where you said a dynamic array was required. The closest you got was saying "I want", which clearly says that you have a choice. Therefore, I suggested a better choice.
wel i did not blame you for that, i mearly pointed out the fact. since my original post was not clear enough for you.

>Then make it shorter for posting. There's a sticky at the top of this forum that tells you how to post like an intelligent human being.
i did make it short for posting. look at my post....

>Then you should say "thanks" and leave it because my comment was accurate when you posted. As I said, I'm not psychic, so I don't know what changes you made after you posted.
well i added nothrow bofore you suggested, so i was just letting u know. But thanks anyways.

>BS. Maybe you should take some lessons in reading for comprehension, because the fourth post in this thread answers your question fully. If it doesn't, you asked the wrong question.
thats funny. Read the first line in the 5th post and then see who should take lessons.

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Narue

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Re: help with dynamic memory

#15

May 14th, 2007

>Read the first line in the 5th post and then see who should take lessons.
I still think it's you. You see, you had some weird looping problem, but my code worked perfectly. So, since I answered the question you asked, and your broken attempt at my answer didn't work, I didn't answer your question? That's some good logic, and it explains why you can't write working code. Please don't take your incompetence out on me.

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m3an

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Re: help with dynamic memory

#16

May 14th, 2007

>Have I still not answered your question?

You have answered my question. Thanks
I was not looking for a handout if that was the impression.
I want to understand what i am doing. Your code is helpful.
Programming can be frustrating sometimes, and your remarks didnt help at all.....but i do apologize.

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m3an

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Re: help with dynamic memory

#17

May 14th, 2007

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Originally Posted by Narue

>Read the first line in the 5th post and then see who should take lessons.
I still think it's you. You see, you had some weird looping problem, but my code worked perfectly. So, since I answered the question you asked, and your broken attempt at my answer didn't work, I didn't answer your question? That's some good logic, and it explains why you can't write working code. Please don't take your incompetence out on me.

I didnt say your code wasnt right....wheres the quote???.