Thread: ordered linked list

[code]STU= (struct person_t ) malloc(sizeof(lperson_t))[code] that means that I should change this line to the malloc line right

Code:

assert(STU != NULL);

Code:

  do
   {
      printf("\n\n"
             "1. Enter new record\n"
             "2. Display List\n"
             "3. Quit\n\n");
      printf("Prompt: ");
      fflush(stdout);
      if ( scanf("%d", &Ans) == 1 ) /* get answer */
      {
        fgets(STU->FName,sizeof(STU->FName),stdin);
         if (STU == NULL)
         {
            perror("PERSON");
            exit(EXIT_FAILURE);
         }

Is there anything here tha may have unallocated memory?

Code:

 fgets(STU->FName,sizeof(STU->FName),stdin);

is says to get it but it dose not allicatit. so i should change it to

Code:

 fgets(STU->FName),malloc(sizeof(STU->FName),stdin);

so that it gets it and allicated it as well

What??????

You seriously need to RTM on malloc().

Actually I'm starting to wonder if redmontab has ever studied a sorting algorithm before. Or if he's had any prior experience with C at all.

http://en.wikipedia.org/wiki/Merge_sort

im very new at this. And it is a little hard to understand on my own. THe book that i have dose not help me out to much. Some times it makes it worse.

so I wnat the fgets to read the who ling. THe way I have it [code] fgets(STU->FName,sizeof(STU->FName),stdin);[code] I;m only reading the first name and not my whol structure. SO i need to change it to

Code:

 fgets(PERSON),malloc (sizeof(Person));

this is because i thave my Structure person_T defined to call as PERSON. Is this correct. Soory if im not geeting this. I appreciate all of you help and patience with me

Also don't forget that malloc() can FAIL. So check the returned pointer BEFORE you use it!

Also look at calloc() if you want to allocate a block of 'n' structures. (And unlike malloc it will initialize the memory to zeroes too).

::sick of this::
Since you don't want to _LEARN_. . .

Code:

STU = malloc(sizeof *STU);
if (STU == NULL){
    printf("Out of memeory");
    exit(0);
}

Insert this before your first fgets() as mentioned above.

know i get the error 87 H:\lab4a.cpp invalid conversion from `void*' to `PERSON*'

Code:

 STU = malloc(sizeof *STU);

how do i do that. Im using the dev-c ++ complier

Im getting this error can someone help me please
117 H:\lab4a.cpp invalid conversion from `void*' to `PERSON*' the orange line is where im getting the error

Code:

/****************************************************************
FILE NAME: lab4.cpp
DESCRIPTION: This program will ask the user if the want to read a file or input 
             data.  Check the file to see if there is data if that is the first
             request. IF not data go back to the options.  Have user add data. 
             Send that data to an ordered linked list then save the data to a 
             file.  Also have the options to show data from file or quit.  .
DATE: October 22, 2006
DESIGNER: Tabatha Mitchell
ASSIGNMENT: Lab4
FUNCTIONS: PERSON* InsertNode (PERSON *Top, PERSON *Node )
           amend_file
           show_file
********************************************************************/
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <malloc.h>


#define Nlen    26

typedef struct person_t { //structure that will sort that data for PERSONS
   char FName[Nlen];
   char LName[Nlen];
   char Sex;
   char Grade;
   struct person_t *Next;
  } PERSON;

struct person_t  *Top = NULL;    //used for the InsertNode set to empty       
struct person_t  *Node = NULL;   //used for the InsertNode set to empty


/****************************************************************
FUNCTION: PERSON* InsertNode
DESCRIPTION: put the sturctured list into the ordered linked list
INPUT:
   Parameters:  The parameters as going to be the last name in the structured 
                list it is going to take the last name and sort it into an 
                ordered linked list   
   Keyboard:  none 
    File: none
OUTPUT:
   Return Value: last name in an ordered linked list 
   Parameters: last name ordered linked list 
   Display: none 
   File: none 
CALLS TO: none 
***************************************************************/

PERSON* InsertNode (PERSON *Top, PERSON *Node )
{
PERSON *Here, /* Node being compared to new node */  
*Prev; /* Node in front of Here node */

    if (Top == NULL)/* List is empty - Place new node at top of list */
      Top = Node;
         else { /* Top != NULL *//* Start at Top of list */
          Here = Top;
          
    strcmp (Here->LName , Node->LName);             
     Node->Next = Top;
     Top = Node;
    
        //  else {/* Search for place to insert new node */
          //  Prev = Top;
          //  Here = Prev->Next;
 
   while ( (Here != NULL) &&(Here->LName < Node->LName) ) {
       Prev = Here;
       Here = Here->Next;
        }/* Insert into list at found spot */
        
Node->Next = Prev->Next;
Prev->Next = Node;
} /* end of Top != NULL */
return Top;
}
/*************************************************************
end of  Function to Ordered linked list
***************************************************************/

void amend_file( char file[],PERSON *STU );//used to define amend_file function
void show_file( char file[],PERSON *STU ); //used to define  show_file function 


int main (void)
{
  PERSON *STU;
   int Ans;
   char file[] = "data.txt";
    int Records [100];
     FILE *fin = fopen(file, "a+");
     struct person_t  *Top = NULL;    
	struct person_t  *Node = NULL;
	
    
    
  do
   {
      printf("\n\n"
             "1. Enter new record\n"
             "2. Display List\n"
             "3. Quit\n\n");
      printf("Prompt: ");
      fflush(stdout);
     
     
     
    
       
         
      if ( scanf("%d", &Ans) == 1 ) /* get answer */
     {
        STU = malloc (sizeof (person_t));   //allocate  memory space for the STU
        if (STU == NULL){  //if not enough space tell us out of memory 
       printf("Out of memory");
        exit(0);
            }
        fgets(STU->FName,sizeof(STU->FName),stdin); 
         if (STU == NULL)
         {
            perror("PERSON");
            exit(EXIT_FAILURE);
         }
         switch(Ans)
         {
            case 1:
               amend_file(file, STU);  //calls the amend file function 
              break;
           
            case 2:
               show_file(file, STU);  //calls the show file function
               break;
           
            case 3: default:
               Ans = 3;
               break;
         }
      } /* /get answer */
   }
    
    
     while ( Ans != 3 );
    
      fflush(stdout);
      free(STU);
      getchar ();
   return EXIT_SUCCESS;
}

/****************************************************************
FUNCTION:  amend_file
DESCRIPTION: this will get the input for the use, send it to the linked list 
             and then save it to the file. 
INPUT:
   Parameters: Person structure. and  Person Insertnode
              
   Keyboard: all of the following will be saved in the structure PERSON
             LName= last name
             FName = first name
             Sex=  what gender the person is
             Grade = The persons grade
    File: data.txt  this is where the data is saved. 
OUTPUT:
   Return Value:  Send The PERSONS STU to the InsertNode put data into list the 
                save to file
   Parameters: InsertNode, LName, FName, Sex, Grade 
   Display: none
   File: data.txt. the PERSONS STU in ordered link list format Lname, FName,
          Sex, Grade 
CALLS TO:  List of all user-generated functions called
***************************************************************/
void amend_file( char file[], PERSON *STU )
{
     int i;
   assert(STU != NULL);
    STU = (struct person_t *) malloc(sizeof(person_t));
   FILE *fin = fopen(file, "a+");
   if ( fin == NULL )
   {
      perror(file);
      exit(EXIT_FAILURE);
   }
   printf("Enter new record: ");
   printf ("\nEnter student's First name ( up to %d letters):", Nlen);
   printf ("\nEnter student's  Last name  ( up to %d letters):", Nlen);
   printf ("\nPlease enter Sex");
   printf ("\nPlease enter Grade\n");
   scanf("%s %s %c %c", STU->FName, STU->LName, &STU->Sex,
      &STU->Grade);
      
    InsertNode (Top, Node);
    fprintf(fin, "%s %s %c %c\n", STU->LName, STU->FName, STU->Sex, STU->Grade);
           fflush(fin);
            fclose(fin); 
      }


/****************************************************************
FUNCTION:  show_file
DESCRIPTION: Reads the data from the file and displays data after sorting if 
            needed.
INPUT:
   Parameters: Person structure. and  Person Insertnode these are read from the 
              file and then  put into the list then displayed. 
   Keyboard: 
   File:  data.txt  this is where the data is saved. 
OUTPUT:
   Return Value:  Send The PERSONS STU to the InsertNode put data into list the
                 save to file
   Parameters: InsertNode, LName, FName, Sex, Grade 
   Display: the order list of people that are saved to the file.  
   File: data.txt. the PERSONS STU in ordered link list format Lname, FName,
         Sex, Grade 
CALLS TO:
***************************************************************/
void show_file ( char file[], PERSON *STU )
{
  assert(STU != NULL);
  int b = 1;
  FILE *fin = fopen(file, "rb");
    
  if (file == NULL)
  {
    perror(file);
    exit(EXIT_FAILURE);
  }
  while (fscanf(fin, "%s %s %c %c", STU->FName, STU->LName, &STU->Sex,
     &STU->Grade)== 4)
  {                   
    
      InsertNode (Top, Node);
      b++;          
    printf("Record %d: %s %s %c %c\n", b, STU->FName, STU->LName,
       STU->Sex, STU->Grade);
  }
  fclose(fin);
}