Program to show Basic interactive linked list

#include "stdio.h"
#include "stdlib.h"

struct NODE
{
int number;
struct NODE *next;
};

int search_value(struct NODE *llist, int num);
void append_node(struct NODE *llist, int num);
void display_list(struct NODE *llist);
void delete_node(struct NODE *llist, int num);

int main(void) {
int num = 0;
int input = 1;
int retval = 0;
struct NODE *llist;

llist = (struct NODE *)malloc(sizeof(struct NODE));
llist->number = 0;
llist->next = NULL;

while(input != 0) {
printf("\n-- Menu Selection --\n");
printf("0) Quit\n");
printf("1) Insert\n");
printf("2) Delete\n");
printf("3) Search\n");
printf("4) Display\n");
scanf("%d", &input);

switch(input)
{
case 0:
default:
printf("Goodbye ...\n");
input = 0;
break;
case 1:
printf("Your choice: `Insertion'\n");
printf("Enter the value which should be inserted: ");
scanf("%d", &num);
append_node(llist, num);
break;
case 2:
printf("Your choice: `Deletion'\n");
printf("Enter the value which should be deleted: ");
scanf("%d", &num);
delete_node(llist, num);
break;
case 3:
printf("Your choice: `Search'\n");
printf("Enter the value you want to find: ");
scanf("%d", &num);
if((retval = search_value(llist, num)) == -1)
printf("Value `%d' not found\n", num);
else
printf("Value `%d' located at position `%d'\n", num, retval);
break;
case 4:
printf("You choice: `Display'\n");
display_list(llist);
break;
} /* switch */
} /* while */

free(llist);
return(0);
}

void display_list(struct NODE *llist) {
while(llist->next != NULL) {
printf("%d ", llist->number);
llist = llist->next;
}

printf("%d", llist->number);
}

void append_node(struct NODE *llist, int num) {
while(llist->next != NULL)
llist = llist->next;

llist->next = (struct NODE *)
malloc(sizeof(struct NODE));
llist->next->number = num;
llist->next->next = NULL;
}

void delete_node(struct NODE *llist, int num) {
struct NODE *temp;
temp = (struct NODE *)malloc(sizeof(struct NODE));

if(llist->number == num) {
/* remove the node */
temp = llist->next;
free(llist);
llist = temp;
} else {
while(llist->next->number != num)
llist = llist->next;

temp = llist->next->next;
free(llist->next);
llist->next = temp;
}
}

int search_value(struct NODE *llist, int num) {
int retval = -1;
int i = 1;

while(llist->next != NULL)
{
if(llist->next->number == num)
return i;
else
i++;

llist = llist->next;
}

return retval;
}

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