Improve company productivity with a Business Account.Sign Up


Linking Linked List To Hard Disk

Posted on 2006-07-19
Medium Priority
Last Modified: 2008-03-06
A simple linked list--

struct node{
int data;
node *next;

Generally when we create LL it gets created in RAM , what if I want to store it hard disk so that I can add / delete more nodes to it.

Question by:sinha_anshul26
  • 3
  • 3

Assisted Solution

sin_ earned 120 total points
ID: 17140890

Since it doesn't make any sense to store the pointers in the hard disk, you can store the data of the linked list into the hard disk by writing method like:

void makePersistent(NODE* root)
   // get each element and store the values in some file.

NODE* getPersistentList()
   //Read from the file.
   //create the link list and associated next ptrs.
   //return it.

The bottom line is, you store the data of the linked list, not the ptrs.

Author Comment

ID: 17143413
Hi Sin_
Just to confirm I got it right...
you  mean to say,(In other words) that there is no way that we can store data at a specific location of the Hard disk (using pointers)?

I read somewhere that OS does this to manage files using FAT file system

Accepted Solution

manish_regmi earned 80 total points
ID: 17143899
In Fat it is not pointers of address but the pointers of block.

for eg. if a file occupies four blocks in block 3 5 6 9,

fat 3 points to 5 points to 6 points to 9.
it means a 32 bit fat value has block number 5.

No there is no way you can store pointers in disk. In virtual memory system you get different address each time you run (esp in dynamically allocated memory).

Manish Regmi
Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.


Expert Comment

ID: 17144178
That's right Anshu! Compiler generates the virtual memory addresses, which  are mapped to a physical page address by MMU while running the application. Therefore, everytime you run the application, you will find that your pointer is pointing to a different address.

Just imagine if you store this address; it may be a garbage next time. Persistence mechanism works by storing the content; you can reconstruct the data structure while reading it back.

Hope it helps.


Author Comment

ID: 17145400
>>Hope it helps
It Helped alot ...thank you both of you

Author Comment

ID: 17145443
Oh !! I choose the other way round sin_ 's  answer should be  Accepted and manish's assisted.
But any way thank you both for  helping


Expert Comment

ID: 17147130
Not a problem! I too didn't know anything about FAT ptrs :)


Featured Post

The 14th Annual Expert Award Winners

The results are in! Meet the top members of our 2017 Expert Awards. Congratulations to all who qualified!

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Often, when implementing a feature, you won't know how certain events should be handled at the point where they occur and you'd rather defer to the user of your function or class. For example, a XML parser will extract a tag from the source code, wh…
Go is an acronym of golang, is a programming language developed Google in 2007. Go is a new language that is mostly in the C family, with significant input from Pascal/Modula/Oberon family. Hence Go arisen as low-level language with fast compilation…
The viewer will learn how to clear a vector as well as how to detect empty vectors in C++.
The viewer will be introduced to the technique of using vectors in C++. The video will cover how to define a vector, store values in the vector and retrieve data from the values stored in the vector.

589 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question