From: Thomas Demmer <demmer AT LSTM DOT Ruhr-UNI-Bochum DOT De>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Writing a struct to disk
Date: Tue, 19 Aug 1997 14:32:20 +0200
Organization: Lehrstuhl fuer Stroemungsmechanik
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CC: kah190 AT psu DOT edu
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Kertis A. Henderson wrote:
> 
> Under djgpp, what is the best way to write a bunch of structs to a
> file?  For instance, I'd like to write a linked list to a file node by
> node, then be able to read the nodes back and reconstruct the list.  A
> node could be something like the following:
> 
> struct node {
>   int number;
>   unsigned char age;
>   char *name;
>   node *next;
> }
> 
> The ints and chars would be relatively easy, but I don't see how a
> variable length string could be written.  Of course, the node pointer
> wouldn't be written.
> 
> If anybody could help me out (or possibly point me in the right
> direction), I'd appreciate it.  Thanks for any input.

What about this:
  int sl;
   ...
   sl= strlen(nd->name);
   fwrite(&sl,1,sizeof(sl),f);
   fwrite(nd->name,sl,sizeof(char),f);
   ...

Read:
   int sl;
   ...
   fread(&sl,1,sizeof(sl),f);
   nd->name = malloc(sl);
   fread(nd->name,sl,sizeof(char),f);

Check the order of parameters of fwrite() and and fread(), because
I usually mix them up... 


-- 
Ciao
Tom

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* Thomas Demmer                                             *
* Lehrstuhl fuer Stroemungsmechanik                         *
* Ruhr-Uni-Bochum                                           *
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* D-44780  Bochum                                           *
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