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7.8

Function to delete nodes from a linked list

Asked by Jaziar in C Programming Language

I need to create a function to add to my code that will delete nodes from a linked list in a order.

I have a program that takes a input file of two values.  Value A is the child node and value B is the parent node

1, 2  ------->  1 is the child and 2 is the parent

the code will take in a file and assign the children nodes to a linked list and then it will create linked list for the parents that have relationships to the children.

So if we had a input file of

A, B
D, B
C, E
B, C
E, D
The below example would work

Search the list for a node with no parents.
Remove it.
Search each remaining node's parents and remove the entry
Repeat until done"
 
>         A  ->  B   ->  D  ->  C   ->  E
> >       |      |              |       |
> >       B      D              E       D
> >       |      |
> >       E      C
>

D has no parents
Remove D and all parent values of D
 
 
>         A  ->  B  ->  C   ->  E
> >       |      |      |
> >       B             E
> >       |
> >       E      C
 
Now E has no parents
Remove E and all parnet values of E
 
>         A  ->  B  ->  C
> >       |      |
> >       B
> >
> >              C
 
Now C has no parents
Remove C and all parent values of B
 
>         A  ->  B
> >       |
> >       B
>  
>
Now B has no parents
Remove B and all parent values of B
 
>         A
>  
 Leaves A - so the order of deletion was  D E C B A 
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#include<string.h>
#include<stdlib.h>
#include<stdio.h>
 
struct node; 
 
struct listNode {
  struct node *data; 
  struct listNode *next; 
  struct listNode *prevNode;
}; 
 
struct node {
  int    value ; 
  struct listNode *listOfParents; 
  struct listNode *entryNode;
};  
 
struct node* insert_value_into_list (struct listNode **head, int value);
void insert_node_into_list (struct listNode **head, struct node *value);
void print_list (struct listNode *head); 
void print_total_list (struct listNode *head); 
void addParentToValue (struct node *value, struct node *parent); 
void delete_node_out_of_list(struct listNode **head, struct node *value); 
 
int main(int argc, char *argv[]) {
  struct node *nodeValue; 
  struct node *nodeParent; 
  struct listNode *head = NULL, *current, *next; 
 
  int value, parent; 
  char fileName[100]; 
  FILE *fin = NULL;
 
  printf("\nPlease enter file name : ");
  scanf("%s",fileName);
  fin = fopen(fileName,"r");
  
  if(fin==NULL) {
    printf("Error: can't open file.\n");
    return 1;
  }
 
  while (!feof(fin))   {
    if (fscanf(fin, "%d,%d",&value, &parent) > 0) {
      fprintf(stdout, "** %d,%d\n", value, parent);
      
      printf ("attempting to insert %d\n", parent); 
      nodeParent = insert_value_into_list(&head, parent);
 
      printf ("attempting to insert %d\n", value); 
      nodeValue = insert_value_into_list(&head, value);
      
      printf ("adding parent to the value node\n"); 
      addParentToValue (nodeValue, nodeParent); 
    }
  }
   
  fclose(fin);
  
  printf("Here's the complete list....\n"); 
  print_total_list (head);   
  
  /* free the list */
  for(current = head; current != NULL; current = next)
    next = current->next, free(current);
  
  return 0;
} // end main
 
 
 
void addParentToValue (struct node *value, struct node *parent) {
  insert_node_into_list(&(value->listOfParents), parent); 
} 
 
 
struct node*  insert_value_into_list(struct listNode **head, int value) {
  struct listNode *temp = NULL;
  struct listNode *prev = NULL;
  struct listNode *cur = NULL;
  struct node *returnNode; 
 
  if(*head == NULL) {  // nothing there yet
    *head = (struct listNode *)malloc(sizeof(struct listNode));
    (*head)->next = NULL;
 
    // make the dataNode 
    returnNode = (struct node *)malloc(sizeof(struct node));
    returnNode->value = value;
    returnNode->listOfParents = NULL; 
 
    (*head)->data = returnNode;  
  }
  else {  // traverse to find the right spot
    cur = *head;
    temp = (struct listNode *)malloc(sizeof(struct listNode *));
    while (cur != NULL && value > cur->data->value) { 
      prev = cur;
      cur = cur->next;
    }
 
    if(prev == NULL) {   // should go at start
      if (value != cur->data->value) { // not already in the list
	temp->next = *head;
	
	// make the dataNode 
	returnNode = (struct node *)malloc(sizeof(struct node));
	returnNode->value = value;
	returnNode->listOfParents = NULL; 
	
	temp->data = returnNode;
	*head = temp;
      }	   
      else {
	returnNode = cur->data;
    temp = NULL; 	
      }
    }
    else {
      if (cur == NULL) { // should go at end
	// make the dataNode 
	returnNode = (struct node *)malloc(sizeof(struct node));
	returnNode->value = value;
	returnNode->listOfParents = NULL; 
	
	temp->data = returnNode; 
	temp->next = cur;
	prev->next = temp;
      }
      else if (value != cur->data->value) { // not already in the list
	// make the dataNode 
	returnNode = (struct node *)malloc(sizeof(struct node));
	returnNode->value = value;
	returnNode->listOfParents = NULL; 
	
	temp->data = returnNode; 
	temp->next = cur;
	prev->next = temp;
      }	   
      else {
	returnNode = cur->data;
    temp = NULL;	
      }
    }
  }
 
  return (returnNode); 
 
} // end insert_value_into_list
 
//****************************************************************************************
//         Insert Node into List
//****************************************************************************************
void insert_node_into_list(struct listNode **head, struct node *value) { 
  struct listNode *temp = NULL;
  struct listNode *prev = NULL;
  struct listNode *cur = NULL;
  struct node *returnNode; 
 
  if(*head == NULL) {  // nothing there yet
    *head = (struct listNode *)malloc(sizeof(struct listNode));
    (*head)->next = NULL;
    (*head)->data = value;
    //returnNode = head; 
  }
  else {  // traverse to find the right spot
    cur = *head;
    temp = (struct listNode *)malloc(sizeof(struct listNode *));
    temp->data = value;
    while (cur != NULL && temp->data->value > cur->data->value) { 
      prev = cur;
      cur = cur->next;
    }
 
    if(prev == NULL) {   // should go at start
      temp->next = *head;
      *head = temp;
    }
    else {
      if (cur == NULL) { // should go at end
	temp->next = cur;
	prev->next = temp;
      }
      else if (temp->data->value != cur->data->value) { // already in the list
	temp->next = cur;
	prev->next = temp;
      }	   
      else {  // Nothing to do
      }
    }
  }
} // end insert_node_into_list
 
//****************************************************************************************
//          Delete Node Out Of List
//****************************************************************************************
void delete_node_out_of_list(struct listNode **head, struct node *value) { 
  struct listNode *temp = NULL;
  struct listNode *prev = NULL;
  struct listNode *cur = NULL;
  struct node *returnNode; 
  
  //Need Code HERE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
  
} // end insert_node_into_list
 
//****************************************************************************************
//          Print Total List
//****************************************************************************************
void print_total_list (struct listNode *head) {
  struct listNode *current; 
 
  current = head;
  while(current != NULL)
    {
      printf("%d ", current->data->value);
      printf("  --> "); 
      print_list(current->data->listOfParents); 
      current = current->next;
    }
 
  printf("\n"); 
}
 
//****************************************************************************************
//          Print List
//****************************************************************************************
void print_list (struct listNode *head) {
  struct listNode *current; 
 
  current = head;
  while(current != NULL)
    {
      printf("%d%s", current->data->value, (current->next ? ", " : ""));
	  //printf("%d ", current->data->value); 
      current = current->next;
    }
 
  printf("\n"); 
}
[+][-]04/14/09 02:50 PM, ID: 24143010Expert Comment

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[+][-]04/15/09 07:10 AM, ID: 24148143Accepted Solution

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About this solution

Zone: C Programming Language
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Solution Provided By: TheSailor
Participating Experts: 2
Solution Grade: A
 
[+][-]04/15/09 07:11 AM, ID: 24148162Expert Comment

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