Why does the `search` function doesn't run? - c

Question

I wrote a function to search nodes in a singly linked list. When I run it, it gets stuck while printing the node does or doesn't exist. There's no warning in the code so I am wondering if there's something wrong with my concept of function calls.
I know that curr->CharArr[9] shouldn't be in the function call, but what should I replace with it if I don't use it? Or is it actually acceptable?
This is the function call for searching nodes.
int search(struct LLNode *curr, char* find)
{
while (curr != NULL)
{
if (curr->CharArr[9] == find)
{
return 1;
curr = curr->next;
}
else if (curr->CharArr[9] != find)
{
return 0;
}
}
}
This is the code which calls it:
printf("\nEnter fruit name to search in the linked list: ");
scanf("%s", find);
int result = search(curr,&find);
if (result == 1)
{
printf("%s found in the list.\n", find);
}
else if (result == 0)
{
printf("%s not found in the list.\n", find);
}
And this is the whole function:
#include <stdio.h>
#include <stdlib.h>
struct LLNode
{
char *CharArr[10];
struct LLNode *next;
};
struct LLNode * createNode (char val[])
{
struct LLNode *temp;
temp =(struct LLNode *)malloc(sizeof(struct LLNode));
temp-> CharArr[9] = val;
temp-> next = NULL;
return (temp) ;
};
int search(struct LLNode *curr, char* find)
{
while (curr != NULL)
{
if (curr->CharArr[9] == find)
{
return 1;
curr = curr->next;
}
else if (curr->CharArr[9] != find)
{
return 0;
}
}
}
int main ()
{
struct LLNode *head = NULL;
struct LLNode *curr = NULL;
char find;
printf("The nodes are:\n");
head = curr = createNode ("Apple") ;
printf ("%s\n", curr->CharArr[9]) ;
curr = curr->next;
curr = createNode("Orange");
printf ("%s\n", curr->CharArr[9]) ;
printf("\nEnter fruit name to search in the linked list: ");
scanf("%s", find);
int result = search(curr,&find);
if (result == 1)
{
printf("%s found in the list.\n", find);
}
else if (result == 0)
{
printf("%s not found in the list.\n", find);
}
}

Answer 1

Your code has a lot of problem, that make your code not work:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct LLNode
{
char CharArr[10]; // problem 1: use array of char, not array of pointer of char
struct LLNode *next;
};
struct LLNode * createNode (const char* val)
{
struct LLNode *temp;
temp =(struct LLNode *)malloc(sizeof(struct LLNode));
strncpy(temp-> CharArr, val, 9); // problem 2: assign value to array
temp->CharArr[9] = 0; // be sure to make it null-terminated
temp-> next = NULL;
return (temp) ;
};
int search(struct LLNode *curr, char* find)
{
while (curr != NULL)
{
if (strncmp(curr->CharArr, find, 9) == 0) // problem 3: the way of comparing string
{
return 1; // problem 4: logic of `search` function. Need follow the logic: return 1 if found. You change `cur` pointer after return is do nothing
}
else
{
curr = curr->next; // move to next element if not found in current node
}
}
return 0; // return 0 if not found at all
}
int main ()
{
struct LLNode *head = NULL;
struct LLNode *curr = NULL;
char find[9] = {0};
printf("The nodes are:\n");
head = curr = createNode ("Apple") ;
printf ("%s\n", curr->CharArr) ;
curr->next = createNode("Orange"); // problem 5: assign wrong pointer for new element in linked list
printf ("%s\n", curr->next->CharArr) ;
printf("\nEnter fruit name to search in the linked list: ");
scanf("%s", find);
int result = search(head, find); // problem 6: pass `head` to search, not `curr`
if (result == 1)
{
printf("%s found in the list.\n", find);
}
else if (result == 0)
{
printf("%s not found in the list.\n", find);
}
}
The above code is sample of fix

Answer 2

I`m not really sure, but I think, first of all, I see unattainable code right here
...
if (curr->CharArr[9] == find)
{
return 1;
curr = curr->next; // right here, return statement before this line
}
...
If I'm not mistaken, in following code you want to compare two char arrays:
...
if (curr->CharArr[9] == find)
// some code
curr->CharArr[9] != find
...
but it does not work because you are using array subscript operator here curr->CharArr[9] and that`s just takes tenth symbol of the char array. If you need to compare two strings you need to compare each character of one string with the corresponding character of another string, or just use strcmp() function.

Answer 3

Firstly, the struct should be like this.
struct LLNode
{
char *CharArr;
struct LLNode *next;
};
The search function needs to use strcmp to match string and you should only return when a match is found.
int search(struct LLNode *curr, char* find)
{
while (curr != NULL)
{
if (strcmp(curr->CharArr, find) == 0)
return 1;
curr = curr->next;
}
return 0;
}
And in your main function, you need to pass in head to the search function. curr points to the latest node you inserted. And curr->next needs to be allocated first to have it be part of the linked list.
curr->next = createNode("Orange");
curr = curr->next;
printf ("%s\n", curr->CharArr) ;
printf("\nEnter fruit name to search in the linked list: ");
scanf("%s", find);
int result = search(head, find);