Program: 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", #);
append_node(llist, num);
break;

case 2:
printf("Your choice: `Deletion'\n");
printf("Enter the value which should be deleted: ");
scanf("%d", #);
delete_node(llist, num);
break;

case 3:
printf("Your choice: `Search'\n");
printf("Enter the value you want to find: ");
scanf("%d", #);
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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