So for a class of mine I need to write a linked list in C, which adds or deletes items as they are read from a file, and as they are inserted, they are placed in order via insertion sort. Each line in the file contains a name, followed by either a or d, which states whether to add or delete that name.
I understand the concept of linked lists, and have implemented them in Java before. For some reason I just can't get this to work in C. Any help would be greatly appreciated.
The first value now makes it into the list, but there is another issue as commented below.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct node
{
char name[42];
struct node *next;
};
void insertNode(char name[42], struct node *head)
{
struct node *new = (struct node*)malloc(sizeof(struct node));
strcpy(new->name, name);
struct node *curr = head;
int finished = 0;
if(!curr)
{
head = new;
return;
}
while(curr->next != NULL) //This loop right here is not working
//it doesn't make it into the loop, curr somehow equals null
//not sure why this isn't working
{
if((strcmp(curr->name, new->name) < 0))
{
new->next = curr->next;
curr->next = new;
finished = 1;
break;
}
curr = curr->next;
}
if(finished = 0)
{
new->next = curr->next;
curr->next = new;
}
}
void removeNode(char name[42], struct node *head)
{
struct node *temp = (struct node*)malloc(sizeof(struct node));
strcpy(temp->name, name);
struct node *curr = head;
while(curr->next != NULL)
{
if(curr->next == temp)
{
curr->next = temp->next;
free(temp->name);
temp->next = NULL;
}
}
}
void FREE(struct node *head)
{
int i;
struct node *temp;
while(head != NULL)
{
temp = head;
head = head->next;
free(temp);
}
}
void printList(struct node *head)
{
struct node *curr = head;
printf("Linked list:\n");
while(curr != NULL)
{
printf("%s\n", curr->name);
curr = curr->next;
}
}
int main(void)
{
FILE *input = fopen("hw7.data", "r");
struct node *head = (struct node*)malloc(sizeof(struct node));
head->next = NULL;
strcpy(head->name, "");
char *tempText = NULL;
char *tempName = NULL;
char *tempOP = NULL;
size_t lineLen;
int i = 0;
getline(&tempText, &lineLen, input);
while(!feof(input))
{
tempName = strtok(tempText, " ");
tempOP = strtok(NULL, "\n");
if(i == 0)
{
strcpy(head->name, tempName);
i = 1;
}
if(tempOP[0] == 'a')
{
insertNode(tempName, head);
}
else
{
removeNode(tempName, head);
}
getline(&tempText, &lineLen, input);
}
printList(head);
fclose(input);
FREE(head);
return 0;
}
Here is the data file:
Beverly a
Kathy a
Radell a
Gary a
Chuck a
David a
kari a
Tom a
Tanya a
Scott a
Beverly d
Brenda d
Kathy a
Gary a
WenChen a
Chuck a
Mike a
Emanuel a
Linda a
Bernie a
Hassan a
Brian a
Gary d
Kathy d
Gary a
Eunjin a
Kathy a
Brenda a
Jun a
Peanut a
Travis a
