Linked List in C help

[dave120]

Hello,

I'm trying to make a program that uses a linked list to store a first and last name of people. I'm eventually going to make it read from a file to get this info but for now it just gets input manually from the menu.

The program compiles and runs fine without errors, but I'm having an issue when I try and display it of whatever the most recent name I added being shown for each person in the list. I think my delete function needs work too, but I'm trying to work out one thing at a time. My code that I have so far is below:

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

struct node
{
	char* fname;
	char* lname;
	struct node* next;
};


void insert(struct node** head, char* fname, char* lname)
{
	struct node* newnode;
	struct node* crnt;

	// Create the node that will be inserted
	newnode = (struct node*)malloc(sizeof(struct node));
	newnode->fname = fname;
	newnode->lname = lname;

	// Insert into empty list
	if(*head == NULL)
	{
		newnode->next = NULL;
		*head = newnode;

		return;
	}

	// Insert at the front of the list
	if(lname != (*head)->lname)
	{
		newnode->next = *head;
		*head = newnode;
    
		return;
	}


	// Find the correct place to insert the node
	crnt = *head;
	while(crnt->next != NULL && crnt->next->lname != lname)
	// 
	{
		crnt = crnt->next;
	}

	// Insert the node into the middle of the list

	newnode->next = crnt->next;
	crnt->next = newnode;
}

int deleteNode(struct node** head, char* fname, char* lname)
{
	struct node* temp;
	struct node* crnt;	

	if((*head) == NULL)
		return 0;

	// Delete the head if it's the node we're looking for
	// (including if it's the only node)
	if(((*head)->lname == lname) && ((*head)->fname == fname))
	{
		temp = *head;
		(*head) = (*head)->next;
		free(temp);
		return 1;
	}

	// Track down the node to delete
	crnt = *head;
	while(crnt->next != NULL && crnt->next->lname != lname)
		crnt = crnt->next;

	// the value we're looking for isn't present
	if(crnt->next == NULL || crnt->next->lname != lname)
		return 0;

	// Delete the target node
	temp = crnt->next;
	crnt->next = crnt->next->next;
	free(temp);
	return 1;
}


void printList(struct node* head)
{
	struct node* crnt = head;
	
	// Loop through each node in the list printing its value
	while(crnt != NULL)
	{
		printf("%s %s\n", crnt->fname, crnt->lname);
		crnt =
	}
}

int main(void)
{
	struct node* head = NULL;
	int choice;
	int number;
    char fname[1024];
	char lname[1024];

	printf("Welcome to linked list program!!\n");

	do
	{
		printf("Make a choice:\n");
		printf("1) Add a Name\n");
		printf("2) Delete a Name\n");
		printf("3) Print the list\n");	
		printf("0) Quit\n");

		scanf("%d",&choice);

		switch(choice)
		{
		case 1:
			//Insert case
			printf("Enter the First Name to insert\n");
			scanf("%s",&fname);
			
			printf("Enter Last Name:");
			scanf("%s",&lname);
			insert(&head, fname, lname);
			break;
		case 2:
			// Delete case
			printf("Enter the Name to delete\n");
			scanf("%s %s",&fname,&lname);
			if(deleteNode(&head,fname,lname))
				printf("Deleted\n");
			else
				printf("That node didn't exist\n");
			break;

		case 3:
			// Print case
			printList(head);
			break;
		case 0:
			// Quit
			printf("Thanks for using the program!\n");
			break;
		default:
			printf("That's not a valid option\n");
		}
	}while(choice != 0);

	system("PAUSE");
	return 0;
}

[redhead]

but I'm having an issue when I try and display it of whatever the most recent name I added being shown for each person in the list.

// Insert at the front of the list
	if(lname != (*head)->lname)
	{
		newnode->next = *head;
		*head = newnode;
    
		return;
	}

Isn't this a false way of doing it ??
you will never reach the while loop for inserting your node.
Unless your added node is the exact same as the very first node in your list.

For some further thoughts on this subject, you might want to read teh Pointer error thread.

For some fun with how to handle pointers, you might want to read my example in the File-I/O arrays thread.

[dave120]

Thanks for the help.

I still haven't been able to fix this issue however. It seems to add nodes correctly but it always just outputs however many when I print with just the most recent values.

The code you referenced I've taken out just to simplify things and make it so it only adds names at the end of the list since the way I'm going to search it won't care what order they're in.

Apparently it inserts nodes as it always ends up with the right number of names in the list. I just can't figure out if I'm referencing something wrong when I print them out or if it's actually replacing every name with the most recent in the list.