Question

I was trying to write a function that deletes a node from the linked list, though I was having trouble.

Here is my algorithm:

• Get the name of the node that I want to delete
  (every node has 3 details in it: name/age/gender)
• Then I find its place in the list
• and then I pass it forward

For example

Friend -> next = friend -> next -> next..

Though I need to find the first node in the linked list, and I’m not sure how to get to it.
This is what I’ve written:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdlib.h>
typedef struct friend
{
    char *name;
   int age;
   char gender;
   struct friend* next;
}friend;
void node_delete(friend* delete)
{
 friend* temp = malloc(sizeof(friend)); 
 char name[256];
 int i = 0, j =0; // Not being used, though I'd use it
 printf ("Please enter the friend's name you want to delete: \n");
 fgets (name, 256, stdin); // Getting the name of the person the user wants to delete
 fgets (name, 256, stdin);
 while (0 == (strcmp(temp -> next -> name, delete -> next -> name))) // As long as the           
 // name doesnt match, it'll go to the next name in the linked list
 {
       temp = friend -> next; // Going to the next name in the linked list
 }
 temp -> next = temp -> next -> next; // Replacing the node with the node after it..
// for ex. if I have 1 -> 2 -> 3, it'll be 1 -> 3
 free (delete);
}

Answer 1

Well, you have had a good crack at this.

I’m not entirely sure about your question but here is what I think you might be trying to do:

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

typedef struct friend
{
    char *name;
    int age;
    char gender;
    struct friend* next;
}friend;


void node_delete(const char* name, friend* stFriend)
{
    if (!stFriend->next) //end of list
    { 
        printf("%s is not a friend!\n", name);
    }
    else if ( !strcmp(name, stFriend->next->name) ) //name matches! remove link
    {     
        //here's where you can free your unwanted friend ptr ~NB: are you sure this friend is not a friend of someone else?
        //free(stFriend -> next);    
        stFriend->next=stFriend->next->next;
        printf("%s is no longer a friend!\n", name); 
    }
    else //name does not match -recurse
    {
        node_delete(name, stFriend->next);
    }
}


void print_friends(const friend* pstPerson)
{
    if (pstPerson->next)
    {
        printf("next friend:%s\n", pstPerson->next->name);
        print_friends(pstPerson->next);
    }
    else 
    {
        printf("no more friends :(\n\n");
    }
}

int main()
{
    friend stFriend0, stFriend1, stFriend2, stPerson;
    char name[256]={0};

    stFriend0.name="amber";
    stFriend0.next=0;

    stFriend1.name="betty";
    stFriend1.next=&stFriend0;

    stFriend2.name="catherine";
    stFriend2.next=&stFriend1;

    stPerson.name="violet";
    stPerson.next=&stFriend2;

    printf("%s's friends before:\n", stPerson.name);
    print_friends(&stPerson);

    printf("remove a friend: ");
    fgets (name, 256, stdin);
    strtok(name, "\n");

    node_delete(name, &stPerson);

    printf("\n\n%s's friends after:\n", stPerson.name);
    print_friends(&stPerson);

    printf("\n\n\ndone!\n");

    return 0;

}

online demo.

It assumes that your node_delete(friend* delete) function takes a person, with some friends in the linked list and removes a friend who’s name matches the stdin input.

(i also added another little function so you can see how much fun a linked list can be!)