CODEWITHSUNDEEP
clinked-list
user5464683
user5464683

Reputation:

Adding nodes to the end of a singly linked list

I have problems when adding nodes to a singly linked list, for some reason the

if(current->next == NULL)

gets skipped when the list is empty, and this causes a seg fault when I display the list... I'm really confused as to why it's getting skipped any ideas?

 void addToList(node** head, char name[30], int groupSize, boolean inRest){
     //create new node
     node *newNode = (node*)malloc(sizeof(node));

     if (newNode == NULL) {
         fprintf(stderr, "Unable to allocate memory for new node\n");
         exit(-1);
     }

     InitNodeInfo(newNode, name, groupSize, inRest);
     node *current = head;
     //check for first insertion
     if (current->next == NULL) {
         current->next = newNode;
         printf("added at beginning\n");
     } else {
         //else loop through the list and find the last
         //node, insert next to it
           while (current->next != NULL) {
               current = current->next;
           }
           current->next = newNode;
           printf("added later\n");
           *head = current;
     }

     if (debug == FALSE) {      //debug mode...
         printf("Pushed the value %d on to the stack\n", groupSize);
     } else {
         printf("\n\nATTENTION : Group cannot be added, the name entered already exists!\n\n");
     }
}

Upvotes: 3

Views: 49

Answers (1)

Pynchia
Pynchia

Reputation: 11580

Assuming an empty list has head == NULL

this should work (I have no means of trying it now)

 void addToList(node** head, char name[30], int groupSize, boolean inRest){
    //create new node
    node *newNode = (node*)malloc(sizeof(node));

    if(newNode == NULL){
        fprintf(stderr, "Unable to allocate memory for new node\n");
        exit(-1);
    }

    InitNodeInfo(newNode, name, groupSize, inRest);
    node *current = *head;
    //check for first insertion
    if(current == NULL){
        // make head point to the new node
        *head = newNode;
        printf("added at beginning\n");
    }
    else
    {
        //else loop through the list and find the last
        //node, insert next to it
          while (current->next != NULL) {
            current = current->next;
          }
          current->next = newNode;
          printf("appended\n");
    }
    // mark the element as the last one
    newNode->next = NULL;

    if (debug == FALSE) {//debug mode...
         printf("Pushed the value %d on to the stack\n", groupSize);
    }
    else{
        printf("\n\nATTENTION : Group cannot be added, the name entered already exists!\n\n");
    }
}

Upvotes: 1

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