Something wrong with strcmp? - c

Question

My assignment is to read a file in to a linked list. The file contains a name and a letter indicating what to do with the name, either add or delete from list. The file is in this format:
Kathy a
Beverly a
Chuck a
Radell a
Gary a
Roger d
and so on...
The problem comes when i try to split up the name and the operation. The strcmp() doesn't even recognize the op_code variable in my code. I printed out both the name and the op_code and they print right unless i put a character near the op_code.
Here's my code:
//Tristan Shepherd
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct node
{
char name[42];
struct node *next;
};
void printList(struct node *head)
{
struct node *current = head;
while (current)
{
printf("3 %s\n", current->name);
current = current->next;
}
}
void addFront(struct node **head, char *newname)
{
struct node* newnode = (struct node*)malloc(sizeof(struct node));
strcpy(newnode->name, newname);
newnode->next = (*head);
(*head) = newnode;
}
void delete(struct node **head, char *namedelete)
{
struct node* temp = *head, *prev;
if (temp != NULL && temp->name == namedelete)
{
*head = temp->next;
free(temp);
return;
}
while (temp != NULL && temp->name != namedelete)
{
prev = temp;
temp = temp->next;
}
if (temp == NULL) return;
prev->next = temp->next;
free(temp);
}
void readfile(struct node *head)
{
FILE *file = fopen("hw8.data", "r");
char tname[42];
char *tempname = (char*)malloc(42*sizeof(char));
char *op_code = (char*)malloc(1*sizeof(char));
while(fgets(tname, sizeof(tname), file))
{
tempname = strtok(tname, " ");
op_code = strtok(NULL, "\n");
printf("%s\n", tempname);
printf("%s\n", op_code);
if (!strcmp(op_code, "a"))
{
addFront(&head, tempname);
}
else if (!strcmp(op_code, "d"))
{
delete(&head, tempname);
}
}
fclose(file);
printList(head);
}
int main()
{
struct node *head = NULL;
readfile(head);
exit(0);
}

Answer 1

The only issue I see with in readFile() is a memory leak.
char *tempname = (char*)malloc(42*sizeof(char));
char *op_code = (char*)malloc(1*sizeof(char));
should just be
char *tempname;
char *op_code;
strtok() breaks up the string in place, it does not produce a copy of the string, so no need to allocate extra memory.
I do see some issues in delete() however
You should be using strcmp() here instead of ==, like you do in readfile()
if (temp != NULL && temp->name == namedelete)
while (temp != NULL && temp->name != namedelete)
You may also need to initialize prev.
With your code as-is, add seemed to be working fine, and with my changes, delete looks ok.