CODEWITHSUNDEEP
clinked-list
user12239061
user12239061

Reputation:

Delete function in linked-list

Do you understand why when i call the delete function here the output become an infinite loop? Without that function the code works.

int main(){

    node *head = NULL;

    end(&head);
    begin(&head);
    begin(&head);
    end(&head);
    begin(&head);
    end(&head);
    begin(&head);
    delete(&head);
    display(head);

    return 0;
}

void delete(node **head){
    node *tmp,*prev = NULL;
    int num;
    printf("Insert the number that you want to delete: ");
    scanf("%d",&num);
    tmp = *head;
    if (tmp->data == num){
        *head = tmp->next;
        free(tmp);
        return;
    }
    while(tmp->data!=num && tmp!=NULL){
        prev = tmp;
        tmp = tmp->next;
    }

    if(tmp == NULL){
        return;
    }
    prev->next = tmp->next;
    free(tmp);
}

Those are my other function:

void begin(node **head){
    node *new;
    int num;
    new = malloc(sizeof(node));
    if(new ==  NULL){
        perror("malloc");
        EXIT_FAILURE;
    }
    printf("Insert number at the beginning: ");
    scanf("%d",&num);
    new->data  = num;
    new->next = *head;
    *head = new;
}

 void end(node **head){
    int num;
    node *tmp,*new;
    new = malloc(sizeof(node));
    if(new == NULL){
        perror("malloc");
        EXIT_FAILURE;
    }
    printf("Insert number at the end: ");
    scanf("%d",&num);
    new->data = num;
    tmp = *head;
    if(tmp == NULL){
        tmp = malloc(sizeof(node));
        tmp->data = num;
        tmp->next = NULL;
    }
    while(tmp->next!=NULL){
        tmp = tmp->next;
    }
    new->next = NULL;
    tmp->next = new;
}


void display(node *head){
    node *tmp;
    if(head == NULL){
        printf("Empty list");
    }
    else{
        while(tmp!=NULL){
            printf("%d ",tmp->data);
            tmp = tmp->next;
        }
    }
}

Upvotes: 1

Views: 74

Answers (2)

user12239061
user12239061

Reputation:

Ok i understand the problem. I forgot to add tmp = head in the else{} condition in the display() function

Upvotes: 1

sumit
sumit

Reputation: 31

temp != NULL condition should be ahead of temp->data != num inside while loop. Because if the temp reaches to the end of list without any match then temp will be NULL and you can't have check value(temp->data != num) for NULL pointer.

Upvotes: 1

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