c linked list delete smallest element [closed] - c

Question

Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 6 years ago.
Improve this question
Lists seem really hard for me. I want to find the smallest element in a file: 1 5 8 6 4 8 6 48 9. It's 1 and I want to delete that 1. I can find the smallest element but can not delete it. I find the smallest element place but not the value. I tried copying deleting function from the web, however I cant understand it due to the fact that I'm really new to C. It writes an error that dereferencing to incomplete type. Please help. Post whole code because it should be more convenient to understand.
#include <stdio.h>
#include <stdlib.h>
typedef struct linkedList {
int value;
struct linkedList *next;
} linkedList, head;
linkedList *readList(linkedList *head) {
FILE *dataFile;
dataFile = fopen("duom.txt", "r");
if (dataFile == NULL) {
printf("Nepasisekė atidaryti failo\n");
} else {
printf("Duomenų failą pavyko atidaryti\n");
}
while (!feof (dataFile))
if (head == NULL) {
head = malloc(sizeof(linkedList));
fscanf(dataFile, "%d", &head->value);
head->next = NULL;
} else {
struct linkedList *current = head;
struct linkedList *temp = malloc(sizeof(linkedList));
while (current->next != NULL) {
current = current->next;
}
fscanf(dataFile, "%d", &temp->value);
current->next = temp;
temp->next = NULL;
}
return head;
}
void search(linkedList *head, int *lowest) {
int a[100];
int i = 0;
int minimum;
int b = 0;
linkedList *current = head;
while (current != NULL) {
a[i] = current->value;
current = current->next;
i++;
}
b = i;
i = 0;
minimum = a[0];
while (b > 0) {
if (minimum > a[i]) {
minimum = a[i];
lowest = i;
}
i++;
b--;
}
}
void deleteNode(struct node **head_ref, int key) {
struct node* temp = *head_ref, *prev;
if (temp != NULL && temp->data == key) {
*head_ref = temp->next; // Changed head
free(temp); // free old head
return;
}
while (temp != NULL && temp->data != key) {
prev = temp;
temp = temp->next;
}
if (temp == NULL)
return;
prev->next = temp->next;
free(temp);
}
void printList(linkedList *head) {
linkedList *current = head;
while (current != NULL) {
printf("%d->", current->value);
current = current->next;
}
printf("NULL\n");
return;
}
int main() {
linkedList *A = NULL;
A = readList(A);
search(A);
head = head->next;
minimum = head->value;
headk->next = head->next;
free(head);
printList(A);
return 0;
}

Answer 1

like this
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
typedef struct linkedList{
int value;
struct linkedList *next;
} linkedList, node;
linkedList *readList(void){
FILE *dataFile;
dataFile = fopen("duom.txt", "r");
if(dataFile == NULL) {
perror("file open");
return NULL;
}
int v;
node head = {0, NULL}, *curr = &head;
while (1 == fscanf(dataFile, "%d", &v)){
node *new_node = malloc(sizeof(node));
if(new_node == NULL){
perror("malloc");
break;
}
new_node->value = v;
new_node->next = NULL;
curr = curr->next = new_node;
}
fclose(dataFile);
return head.next;
}
int searchMin(linkedList *head){
if(head == NULL){
fprintf(stderr, "%s: The list MUST NOT be NULL.\n", __func__);
return INT_MIN;
}
int min = head->value;
node *p = head->next;
while(p){
if(p->value < min)
min = p->value;
p = p->next;
}
return min;
}
void deleteNode(node **head_ref, int key){
node *curr = *head_ref, *prev = NULL;
while (curr != NULL && curr->value != key){
prev = curr;
curr = curr->next;
}
if (curr == NULL) return;//not found
if(prev)
prev->next = curr->next;
else
*head_ref = curr->next;
free(curr);
}
void printList(linkedList *head){
node *current = head;
while (current != NULL) {
printf("%d->", current->value);
current = current -> next;
}
puts("NULL");
}
void freeList(linkedList *list){
while(list){
node *temp = list;
list = list->next;
free(temp);
}
}
int main(void){
linkedList *A = readList();
int min = searchMin(A);
printList(A);
deleteNode(&A, min);
printList(A);
freeList(A);
return 0;
}

Answer 2

Please try if this program can help you.
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
struct node {
int data;
struct node *next;
};
void push(struct node **head_ref, int new_data) {
struct node *new_node = (struct node *) malloc(sizeof(struct node));
new_node->data = new_data;
new_node->next = (*head_ref);
(*head_ref) = new_node;
}
void deleteNode(struct node **head_ref, int key) {
struct node *temp = *head_ref, *prev;
if (temp != NULL && temp->data == key) {
*head_ref = temp->next;
free(temp);
return;
}
while (temp != NULL && temp->data != key) {
prev = temp;
temp = temp->next;
}
if (temp == NULL) return;
prev->next = temp->next;
free(temp);
}
void printList(struct node *node) {
while (node != NULL) {
printf(" %d ", node->data);
node = node->next;
}
}
void min(struct node **q) {
struct node *r;
int min = INT_MAX;;
r = *q;
while (r != NULL) {
if (r->data < min) {
min = r->data;
}
r = r->next;
}
printf("The min is %d", min);
deleteNode(q, min);
printf("\n");
}
int main() {
struct node *head = NULL;
FILE *file = fopen("duom.txt", "r");
int i = 0;
fscanf(file, "%d", &i);
while (!feof(file)) {
push(&head, i);
fscanf(file, "%d", &i);
}
fclose(file);
puts("Created Linked List: ");
printList(head);
min(&head);
puts("\nLinked List after Deletion of minimum: ");
printList(head);
return 0;
}
file duom.txt
1 5 8 6 4 8 6 48 9
Test
./a.out
Created Linked List:
9 48 6 8 4 6 8 5 1 The min is 1
Linked List after Deletion of minimum:
9 48 6 8 4 6 8 5 ⏎