Thread: Data structs and pointers

Purpose: to emulate a multi-function program by working via pointers in multipe queues.

objective: to add data to a queue (qemp); work w/ the array (empdata) via (qemp1)...via pointers

Need: next2 pointer initialized to next
next will follow the records as I input them into qemp
next2 will follow the records as I modify them in qemp1

currdata will be initialized to firstdata;

Sample input file:
row1: lname, fname, minit
row2: multiple phone#s
row3: multiple fax#s
row4: multiple email addresses

addis steve d
123-456-1111 123-461-1233 123-454-2345
123-456-1112 123-461-1234 123-454-2346
email1, email2, email3

Code:

 #include "test.h" 

int main(void)
{
  FILE *fin;

  char buffer[MAX];
  QUEUE qemp, qemp1;
  EMP emprec;
  int c;


  //open file
  fin = fopen("firstdata", "r");

  //init q
  qemp.head = qemp.tail = NULL;
  qemp1.head = qemp1.tail = NULL;
  

  //place data into q
  while (fgets( buffer, sizeof buffer, fin ) != NULL ) 
  {
	 sscanf ( buffer, "%s%s%s", &emprec.fname, &emprec.lname, &emprec.mname ) ; 
	 
	 //add multiple records of phone #s, email addresses & faxes*/
	 while ( fgets ( buffer, sizeof buffer, fin ) != NULL ) 
	 {
		//phone #s 
		while ( buffer ) 
		  sscanf ( buffer, "%s", emprec.firstdata[c++].phone );

		c = 0;

		//fax#
		while ( buffer ) 
		  sscanf ( buffer, "%s", emprec.firstdata[c++].fax );

		c = 0;

		//emails
		while ( buffer ) 
		  sscanf ( buffer, "%s", emprec.firstdata[c++].email );

	 }  
  }		


  //addrec to qemp
  addrec ( &qemp, emprec );

//del a phone #
//this is problem...
//delrec ( &qemp1, emprec.firstdata);

  fclose(fin);

return 0;

}

NODE *createlist ( EMP inpdata, NODE *link )
{

  //create a node
  NODE *ptemp = ( NODE * ) malloc ( sizeof ( NODE ) ) ;

  if ( ptemp ) //if not null 
  {
	 //assign data values to pointer
	 ptemp -> record = inpdata;
	 ptemp -> next = link;
	 ptemp -> next2 = ptemp -> next;

  }

  return ptemp;

} 


int addrec ( QUEUE *q, EMP item)
{

  int success = 1; //init value

  //pointer to new node
  NODE *new_node;

  if ( q -> tail == NULL ) 
	 if ( ( q -> tail = createlist ( item, q -> tail ) ) == NULL )	
		success = 0;
	 else
		q -> tail -> next = q -> tail;
  else 
	 if ( ( new_node = createlist ( item, q -> tail -> next ) ) == NULL )  
		success = 0;
	 else
		q -> tail = q -> tail -> next = new_node;

return success;	

} 

int delrec ( QUEUE *q, EMP *dataout)
{

int success = 1;

NODE *del;

   if ( qempty ( q ) )
   {
	  success = 0;
   }  
   else  
   {
	 *dataout = q -> tail -> next -> record;
	 del = q -> tail -> next;
	 q -> tail -> next = del -> next;
	 if ( ( q -> tail == del ) && ( q -> tail -> next == del ) )
	 q -> tail = NULL;
	 free ( del );
   }

return success;

}

int qempty ( QUEUE *q )
{

  return q -> tail == NULL;

} 


#include <stdio.h>
#include <stdlib.h>


#define MAX 100

typedef struct _firstdata
{

  char phone, fax, email;
}firstdata;

typedef struct _EMP
{

  char fname, lname, mname;
  firstdata firstdata[MAX];
	
}EMP;

typedef struct _NODE
{
   EMP record; 
 struct _NODE *next, *next2;

}NODE;


typedef struct _QUEUE
{
 
   NODE *head, *tail;

}QUEUE;  


NODE *createlist ( EMP record, NODE *pnext );
int addrec ( QUEUE *q, EMP item);
int delrec ( QUEUE *q, EMP *pout);
int qempty ( QUEUE *q );

Sample File:

Header File is at the end of the code;;;beginning line: #define MAX 100

This additional info will address the problem

//delrec ( &qemp1, emprec.firstdata); note this should be
//delrec ( &qemp1, emprec.curdata);

The problem is I don't know how or where to (in header file, in queue functions, et al )init curdata to firstdata; next2 to next so that as I perform processes on the records I have constantly updating next2->curdata via pointers

This is the deal:
read in the records using as linked list queue

modify records using a different queue via pointers with next2 pointer (i.e. q2->next2->curdata

I hope this helps...if I knew the correct verbage, I'm sure this would be a two line sentence.....