Dynamic array of pointers to structures - doubt

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Dynamic array of pointers to structures - doubt

 
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  #1
Sep 11th, 2008
Hi,

I need to implement a dynamic array of pointers to structures.Here's what I've done

C++ Syntax (Toggle Plain Text) 
  1. struct node{
  2.         int freq;
  3.         node *lptr;
  4.         node *rptr;
  5. };
  6.  
  7. class M
  8. {
  9.         private:
  10.         node **A;
  11.         int length;
  12.         public:
  13.         M()
  14.         {
  15.                 length=10;
  16.                 A=new node*[10];
  17.         }
  18.         M(int a)
  19.         {
  20.                 length=a;
  21.                 A=new node*[a];
  22.         }

Firstly, am I right?

Now when I use this in a function..

C++ Syntax (Toggle Plain Text) 
  1.  int i;
  2.  for(i=0;i<length;i++)
  3.   A[i]->freq=i;

I get Segmentation Fault.I'm pretty sure im mucking up pointers somewhere.Any help?
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Re: Dynamic array of pointers to structures - doubt

 
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  #2
Sep 11th, 2008
>Firstly, am I right?
So far, yes.

>I get Segmentation Fault.
Did you allocate memory to the individual pointer or just the array? There are two steps here, first you allocate memory for the pointers in the dynamic array, then you allocate memory to each pointer to hold a node instance.
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Re: Dynamic array of pointers to structures - doubt

 
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  #3
Sep 11th, 2008
ohhh...I did not allocate memory for each pointer to hold a node...so would that be something like...
C++ Syntax (Toggle Plain Text) 
  1. for(i=0;i<length;i++)
  2. A[i]=new node
???
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Re: Dynamic array of pointers to structures - doubt

 
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  #4
Sep 11th, 2008
That's it exactly.
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