I am working on building circular doubly linked list code.
In my code, there are four function- add node, delete node, print clockwise, print counterclockwise. All my code works fine, besides the delete function. The if(recycle->name == x) line seems not working properly, and free(recycle) also doesn't successfully free the recycle node.
My original code are. as follows
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define nameLen 20
struct Node
{
char name[nameLen];
struct Node *left; //next
struct Node *right; //previous
};
struct Node* current;
struct Node* head;
int count = 0;
struct Node* GetNewNode(char *x)
{
struct Node* newNode;
newNode = (struct Node*)malloc(sizeof(struct Node));
strncpy(newNode->name, x, nameLen);
newNode->left = NULL;
newNode->right = NULL;
return newNode;
}
void add_name(char *x)
{
struct Node* temp = current;
struct Node* newNode = GetNewNode(x);
count++;
if(current == NULL)
{
current = newNode;
head = current;
}
else
{
current->left = newNode;
newNode->right = temp;
current = newNode;
current->left = head;
head->right = current;
}
printf("Add %s into database.\n\n", current->name);
}
void delete_name(char *x)
{
int i, j;
struct Node* recycle = current;
if(current == NULL)
{
printf("No data input.");
}
else
{
for (i = 0; i < count; i++)
{
if(recycle->name == x)
{
free(recycle);
j++;
printf("Delete %s from database.\n", x);
}
recycle = recycle->left;
}
if(j == 0)
{
printf("There is no %s in data", x);
}
current = recycle;
}
}
void print_clock(int number)
{
int i;
struct Node* temp = current;
if(temp == NULL)
{
printf("No data input.");
}
else
{
printf("Clockwise: \n");
for(i = 0; i < number; i++)
{
printf("%s ",temp->name);
temp = temp->left;
}
}
printf("\n\n");
}
void print_counter(int number)
{
int i;
struct Node* temp = current;
if(temp == NULL)
{
printf("No data input.");
}
else
{
printf("Counterclockwise: \n");
for(i = 0; i < number; i++)
{
printf("%s ",temp->name);
temp = temp->right;
}
}
printf("\n\n");
}
int main()
{
char s1;
char s2[nameLen];
char name[nameLen];
int number;
while(1)
{
printf("Enter the instruction: ");
scanf("%s %s", &s1, s2);
if (s1 == '+' && sscanf(s2, "%d", &number) == 1)
{
printf("Print out %d name(s) clockwise.\n", number);
print_clock(number);
}
else if (s1 == '-' && sscanf(s2, "%d", &number) == 1)
{
printf("Print out %d name(s) counterclockwise.\n", number);
print_counter(number);
}
else if (s1 == '+' && sscanf(s2, "%s", name) == 1)
{
add_name(s2);
}
else if (s1 == '-' && sscanf(s2, "%s", name) == 1)
{
delete_name(s2);
}
else if (s1 == 'e')
{
printf("Bye.\n");
break;
}
else // No match.
printf("Wrong Input. %s %s\n", &s1, s2);
}
system("pause");
return 0;
}
Statement recycle->name == x checks if two pointers point to the same object in memory. It does not check if two (different) objects in memory have equal content.
Use
if (strcmp(recycle->name, x) == 0) { ...
to check for equal string contents.
Related
I am new to C programming and When I asked user to input a number for some reason my whole program gives this error
Program received signal SIGSEGV, Segmentation fault.
0x0000555555555753 in addData (word=0x7fffffffeb70 "", mode=2) at main.c:202
202 if (temp->next == NULL) {
(gdb)
HERE IS MY CODE
#include <stddef.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>
#define MEMORY 6
#define MAX_word_LENGTH 11
int numberOfwords;
char words[MEMORY][MAX_word_LENGTH];
struct Node{
int data;
char *word;
struct Node *next, *prev;
};
struct Node *head, *tail;
struct Node* DlListDeleteLastNode(struct Node *head);
void addData(char *word, int mode);
void DisplayForward();
struct Node* deletePos(struct Node *head, int pos);
int getPostion(char *targetWord);
bool search(char *targetWord);
//struct Node* deletePos(struct Node *head, int pos);
int countWord(char *wording);
void insert_specified(char *wording, int pos);
int countNodes();
//void init(){
// head = NULL;
// tail = NULL;
//}
int main()
{
char name[100];
//char searchName[] = "barr";
printf("Enter number of words to be stored in the word stream: ");
int input;
scanf("%d", &input);
int i;
int count = 0;
for (i=0; i<input;i++){
count++;
printf("\nEnter name %d : ",count);
scanf ("%[^\n]%*c", name);
//scanf("%s[^\n]",words[i]);
addData(name, 2);
}
//for (int i = 0; i <4; i++) {
// strcpy(words[i],
//}
//insert_specified(searchName, 0);
//printf("%d\n", numberOfwords);
//DlListDeleteLastNode();
DisplayForward();
//int num = countNodes();
//printf("count %d", num);
//deletePos(head, 3);
//bool x = search(searchName);
//printf("%d\n", x);
//printf("%d\n", numberOfwords);
//DisplayForward();
//fflush(stdin);
printf("\nEntered names are:\n");
for(i=0;i<6;i++)
puts(words[i]);
}
int isEmpty(struct Node *h){
if(h==NULL)
return 1;
else
return 0;
}
void addData(char *word, int mode){
if (mode == 1) {
for (int i=0; i<5; i++) {
if (strcmp(words[i],word) == 0) {
//printf("found\n");
//printf("FOUND%s\n", word);
int x = getPostion(word);
//printf("index found %d/n", x);
//deletePos(head, x);
struct Node* temp = head;
struct Node* temp2 = NULL;
while (x > 1) {
temp = temp->next;
x--;
}
if (temp->next == NULL) {
head = DlListDeleteLastNode(head);
}
else {
temp2 = temp->prev;
temp2->next = temp->next;
temp->next->prev = temp2;
free(temp);
temp = NULL;
}
break;
}
//x index = getPostion()
}
if (numberOfwords >= 5) {
DlListDeleteLastNode(head);
struct Node *ptr;
ptr= malloc(sizeof *ptr);
ptr->word = malloc(sizeof(char) * 12);
//char nimI[20];
//baru->nim = malloc(12 * sizeof(char));
//strcpy(ptr->word, word);
if(head==NULL)
{
ptr->next = NULL;
ptr->prev=NULL;
strcpy(ptr->word, word);
//ptr->word= word;
head=ptr;
//head = ptr;
//tail = ptr;
}
else
{
//ptr->word=word;
strcpy(ptr->word, word);
ptr->prev=NULL;
ptr->next = head;
head->prev=ptr;
head=ptr;
}
numberOfwords++;
}
else {
struct Node *ptr;
ptr= malloc(sizeof *ptr);
ptr->word = malloc(sizeof(char) * 12);
//char nimI[20];
//baru->nim = malloc(12 * sizeof(char));
//strcpy(ptr->word, word);
if(head==NULL)
{
ptr->next = NULL;
ptr->prev=NULL;
strcpy(ptr->word, word);
//ptr->word= word;
head=ptr;
//head = ptr;
//tail = ptr;
}
else
{
//ptr->word=word;
strcpy(ptr->word, word);
ptr->prev=NULL;
ptr->next = head;
head->prev=ptr;
head=ptr;
}
numberOfwords++;
strcpy(words[numberOfwords], word);
}
}
else {
int flag = 0;
//int numWords = countNodes();
for (int i=0; i<8; i++) {
if (strcmp(words[i],word) == 0) {
//printf("found\n");
//printf("FOUND%s\n", word);
int x = getPostion(word);
//printf("index found %d/n", x);
//deletePos(head, x); //
struct Node* temp = head;
struct Node* temp2 = NULL;
while (x > 1) {
temp = temp->next;
x--;
}
if (temp->next == NULL) {
head = DlListDeleteLastNode(head);
}
else {
temp2 = temp->prev;
temp2->next = temp->next;
temp->next->prev = temp2;
free(temp);
temp = NULL;
}
flag = 1;
//DisplayForward();
//numberOfwords--;
break;
}
//x index = getPostion()
}
printf("\nflag num-> %d\n", flag);
//numberOfwords++;
int numWords = countNodes();
if (numWords >= 5 && flag==0) {
//printf("activated");
int max = 0;
char maxWord[50];
for (int i = 0; i < 8; i++) {
int num = countWord(words[i]);
if (num > max) {
max = num;
//printf("%d", max);
strcpy(maxWord, words[i]);
//printf("word %s\n", maxWord);
}
}
printf("most occured word: %s\n", maxWord);
int mostOccuredWordIndex = getPostion(maxWord);
printf("index: %d\n", mostOccuredWordIndex);
mostOccuredWordIndex--;
insert_specified(word, mostOccuredWordIndex);
DlListDeleteLastNode(head);
}
else if (numWords >= 5) {
//DlListDeleteLastNode(head);
//struct Node *ptr;
//ptr= malloc(sizeof *ptr);
//ptr->word = malloc(sizeof(char) * 12);
//char nimI[20];
//baru->nim = malloc(12 * sizeof(char));
//strcpy(ptr->word, word);
//Get most occured word in words array
//find the position of the most occured word
//int mostOccuredWordIndex = getPostion(maxWord);
//remove last element and insert new word into that position
//if position is in the last index then remove word and replace with the word
//if (mostOccuredWordIndex == 5) {
// printf("occurred");
//}
//
DlListDeleteLastNode(head);
numberOfwords = numberOfwords + 1;
struct Node *ptr;
ptr= malloc(sizeof *ptr);
ptr->word = malloc(sizeof(char) * 12);
if(head==NULL)
{
ptr->next = NULL;
ptr->prev=NULL;
strcpy(ptr->word, word);
//ptr->word= word;
head=ptr;
//head = ptr;
//tail = ptr;
}
else
{
//ptr->word=word;
strcpy(ptr->word, word);
ptr->prev=NULL;
ptr->next = head;
head->prev=ptr;
head=ptr;
}
}
else {
struct Node *ptr;
ptr= malloc(sizeof *ptr);
ptr->word = malloc(sizeof(char) * 12);
//char nimI[20];
//baru->nim = malloc(12 * sizeof(char));
//strcpy(ptr->word, word);
if(head==NULL)
{
ptr->next = NULL;
ptr->prev=NULL;
strcpy(ptr->word, word);
//ptr->word= word;
head=ptr;
//head = ptr;
//tail = ptr;
}
else
{
//ptr->word=word;
strcpy(ptr->word, word);
ptr->prev=NULL;
ptr->next = head;
head->prev=ptr;
head=ptr;
}
numberOfwords = numberOfwords + 1;
strcpy(words[numberOfwords], word);
}
DisplayForward();
numWords = countNodes();
printf("\nnumber of words%d \n", numWords);
}
}
struct Node* DlListDeleteLastNode(struct Node *head) {
struct Node *temp = head;
struct Node* temp2;
while (temp->next != NULL) {
temp = temp->next;
}
temp2 = temp->prev;
temp2->next = NULL;
free(temp);
numberOfwords--;
return head;
}
void DisplayForward() {
//Node current will point to head
struct Node *current = head;
if(head == NULL) {
printf("List is empty\n");
return;
}
printf("[");
int count = numberOfwords;
// while current->next != Null
while(current!=NULL) {
//Prints each node by incrementing pointer.
printf("%s, ", current->word);
current = current->next;
count--;
}
//current = current->next;
//printf("%s]\n", current->word);
//printf("%d", numberOfwords);
}
bool search(char *targetWord) {
int pos = 0;
if(head==NULL) {
printf("Linked List not initialized");
return;
}
struct Node *current = head;
//current = head;
while(current!=NULL) {
pos++;
if(strcmp(current->word, targetWord) == 0) {
printf("%s found at position %d\n", targetWord, pos);
return true;
}
if(current->next != NULL)
current = current->next;
else
break;
}
return false;
//printf("%s does not exist in the list\n", targetWord);
}
int getPostion(char *targetWord) {
int pos = 0;
if(head==NULL) {
printf("Linked List not initialized");
return -1;
}
struct Node *current = head;
//current = head;
while(current!=NULL) {
pos++;
if(strcmp(current->word, targetWord) == 0) {
//printf("%s found at position %d\n", targetWord, pos);
return pos;
}
if(current->next != NULL)
current = current->next;
else
break;
}
return -1;
//printf("%s does not exist in the list\n", targetWord);
}
int countWord(char *wording) {
int count = 0;
for(int i=0;i<6;i++) {
if (strcmp(words[i], wording)==0) {
//printf("found word");
count++;
}
}
return count;
}
void insert_specified(char * wording, int pos)
{
struct Node *ptr;
ptr= malloc(sizeof *ptr);
ptr->word = malloc(sizeof(char) * 12);
struct Node *temp;
int i;
if(ptr == NULL)
{
printf("\n OVERFLOW");
}
else
{
//printf("\nEnter the location\n");
//scanf("%d",&loc);
temp=head;
for(i=0;i<pos;i++)
{
temp = temp->next;
if(temp == NULL)
{
printf("\ncan't insert\n");
return;
}
}
strcpy(ptr->word, wording);
ptr->next = temp->next;
ptr -> prev = temp;
temp->next = ptr;
temp->next->prev=ptr;
printf("Node Inserted\n");
}
}
int countNodes() {
int counter = 0;
//Node current will point to head
struct Node *current = head;
while(current != NULL) {
//Increment the counter by 1 for each node
counter++;
current = current->next;
}
return counter;
}
I tried to ask the user for a number of words it wants to input for my program to store the items in a doubly linked list but instead gives a segmentation fault error
struct Node *head is a global variable which is zero initialized. In addData() you set struct Node* temp = head; and then you deference temp like your stack trace shows which will segfault.
Anyways, before you even get there the 2nd scanf() fails as it the input buffer contains the \n from reading the previous number. The syntax of the format string also looks wrong to me. In any case as you don't check the return value of you are operating on uninitialized data. Here is the minimal fix:
if(scanf(" %99[^\n]*", name) != 1) {
printf("scanf failed\n");
return 1;
}
I also replaced the hard-coded < 8 with < MEMORY to avoid a buffer overflow. Here is an example run:
Enter number of words to be stored in the word stream: 2
Enter name 1 : test
flag num-> 0
[test,
number of words1
Enter name 2 : test2
flag num-> 0
[test2, test,
number of words2
[test2, test,
Entered names are:
test
test2
I have this code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct Node
{
int x;
struct Node *next;
} Node;
void deallocate(Node **root)
{
Node *curr = *root;
while (curr != NULL)
{
Node *aux = curr;
curr = curr->next;
free(aux);
}
*root = NULL;
}
void insert_end(Node **root, int value)
{
Node *new_node = malloc(sizeof(Node));
if (new_node == NULL)
{
exit(1);
}
new_node->next = NULL;
new_node->x = value;
if (*root == NULL)
{
*root = new_node;
return;
}
Node *curr = *root;
while (curr->next != NULL)
{
curr = curr->next;
}
curr->next = new_node;
}
void deserialize(Node **root)
{
FILE *file = fopen("duom.txt", "r");
if (file == NULL)
{
exit(2);
}
int val;
while (fscanf(file, "%d, ", &val) > 0)
{
insert_end(root, val);
}
fclose(file);
}
int largestElement(struct Node *root)
{
int max = INT_MIN;
while (root != NULL)
{
if (max < root->x)
max = root->x;
root = root->next;
}
return max;
}
void deleteN(Node **head, int position)
{
Node *temp;
Node *prev;
temp = *head;
prev = *head;
for (int i = 0; i < position; i++)
{
if (i == 0 && position == 1)
{
*head = (*head)->next;
free(temp);
}
else
{
if (i == position - 1 && temp)
{
prev->next = temp->next;
free(temp);
}
else
{
prev = temp;
// Position was greater than
// number of nodes in the list
if (prev == NULL)
break;
temp = temp->next;
}
}
}
}
int main()
{
Node *root = NULL;
printf("MENU:\n");
printf("if you press 0 the list will be created \n");
printf("if you press 1 the list will be printed on a screen\n");
printf("if you press 2 it deletes the biggest element\n");
printf("if you press 3 the program ends\n\n");
int meniu;
printf("press:\n");
scanf("%d", &meniu);
while (meniu != 3)
{
if (meniu == 0)
{
deserialize(&root);
printf("sarasas sukurtas.\n");
}
if (meniu == 1)
{
for (Node *curr = root; curr != NULL; curr = curr->next)
printf("%d\n", curr->x);
}
if (meniu == 2)
{
int max_element = largestElement(root);
printf("%d max\n", max_element);
deleteN(&root, max_element);
}
printf("press:\n");
scanf("%d", &meniu);
}
deallocate(&root);
return 0;
}
When I compile and run the delete function it only deletes the biggest number first time and if I call it second time it deletes the last number of the list. Can someone help me fix that?
I edited it so all of the code can be seen because it was hard to understand it like I had it before
Your largestElement returns the largest data value in the list.
However, here:
int max_element = largestElement(root);
printf("%d max\n",max_element);
deleteN(&root, max_element);
you use the return value as if it is the position of the node with the largest element.
Instead of largestElement you need a function that returns the position of the element with the largest data value.
It would look something like:
int positionOfLargestElement(struct Node* root)
{
int pos = 0;
int maxpos = 0;
int max = INT_MIN;
while (root != NULL) {
++pos;
if (max < root->x)
{
max = root->x;
maxpos = pos;
}
root = root->next;
}
return maxpos;
}
note: The exact code depends a bit on whether the first node is considered to be position 0 or position 1 but the principle is the same.
I got problem with Singly Linked List problem.
When i inserted something in front of head. head is always have 0 of data.
I think init_list() function is something wrong. I think head of 0 is from randomly initialized data.
anything is fine without head 0 problem.
I'm sure that initializing method is wrong. But I don't know how to solve it..
Here is my I/0 and Desired Output
Input
2
insert 0 1
size
Output I got
1->0->NULL
2
1->0->NULL
Desired Output
1->NULL
1
1->NULL
Here is My Code
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef int Element;
typedef struct LinkedNode {
Element data;
struct LinkedNode* link;
} Node;
Node* head;
void init_list() {
head = (Node*)malloc(sizeof(Node));
head->link = NULL;
}
int is_empty() {
if (head == NULL) return 1;
else return 0;
}
Node* get_entry(int pos)
{
Node* p = head;
int i;
for (i = 0; i < pos; i++, p=p->link){
if (p == NULL) return NULL;
}
return p;
}
int size()
{
Node* p;
int count = 0;
for (p = head; p != NULL; p = p->link)
count++;
return count;
}
void replace(int pos, Element val)
{
Node* node = get_entry(pos);
if (node != NULL)
node->data = val; // replace
}
Node* search_list(Element val)
{
Node* p;
for (p = head; p != NULL; p = p->link)
if (p->data == val) return p;
return NULL;
}
void insert_next(Node * before, Node * node)
{
if (node != NULL) {
node->link = before->link;
before->link = node;
}
}
void insert(int pos, Element val)
{
Node* new_node, * prev;
new_node = (Node*)malloc(sizeof(Node));
new_node->data = val;
if (pos == 0) {
new_node->link = head;
head = new_node;
}
else {
prev = get_entry(pos-1);
if (prev != NULL)
insert_next(prev, new_node);
else free(new_node);
}
}
Node * remove_next(Node * prev)
{
Node* removed = prev->link;
if (removed != NULL) {
prev->link = removed->link;
}
return removed;
}
void delete(int pos)
{
Node* prev, * removed;
if (pos == 0 && is_empty() == 0) {
removed = get_entry(pos);
head = head->link;
free(removed);
}
else {
prev = get_entry(pos-1);
if (prev != NULL) {
remove_next(prev);
free(removed);
}
}
}
void clear_list()
{
while (is_empty() == 0)
delete(0);
}
void print_list()
{
Node* p;
for (p = head; p != NULL; p = p->link)
printf("%d->", p->data);
printf("NULL\n");
}
Node * concat_list(Node * new_node)
{
if(is_empty()) return new_node;
else if(new_node == NULL) return new_node;
else{
Node* p;
p = head;
while (p->link != NULL) {
p = p->link;
}
p->link = new_node;
return head;
}
}
int main(void)
{
Element num;
int pos;
int n, i, j, len;
char c[15];
Node* tmp_head= NULL;
Node* new_head= NULL;
init_list();
scanf("%d", &n);
for (i = 0; i < n; i++)
{
scanf("%s", c);
if (strcmp(c, "insert") == 0) { scanf("%d %d\n",&pos, &num); insert(pos,num); print_list();}
else if (strcmp(c, "delete") == 0) { scanf("%d\n", &pos); delete(pos); print_list();}
else if (strcmp(c, "size") == 0) {printf("%d\n", size()); print_list();}
else if (strcmp(c, "empty") == 0) {printf("%d\n", is_empty()); print_list();}
else if (strcmp(c, "getEntry") == 0) { scanf("%d\n", &pos); printf("%d\n", get_entry(pos)->data); print_list();}
else if (strcmp(c, "search_list") == 0) { scanf("%d\n", &num); printf("%d\n", search_list(num)->data); print_list();}
else if (strcmp(c, "replace") == 0) { scanf("%d %d\n", &pos, &num); replace(pos,num); print_list();}
else if (strcmp(c, "concat_list") == 0) {
tmp_head = head;
init_list();
scanf("%d", &len);
for (j = 0; j < len; j++)
{
scanf("%d %d\n",&pos, &num); insert(pos,num);
}
printf("new_node: ");
print_list();
new_head = head;
head = tmp_head;
head = concat_list(new_head);
print_list();
}
else printf("error\n");
}
return 0;
}
The basic problem is that within init_list, the code only initializes link but not data. I'd suggest instead that you initialize head to NULL and simply use insert to create nodes.
I'm having trouble deleting nodes in a doubly linked list, the program crash and i can't figure out the problem. Can you please help me?
This is the full code that creates new nodes, views them and deletes them.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct Test
{
int id;
};
typedef struct Node {
struct Test structure;
struct Node * next;
struct Node *prev;
}TNode;
typedef TNode* Node;
void NewNode(struct Test p, Node *pp)
{
Node temp;
temp = (Node)malloc(sizeof(struct Node));
temp->structure = p;
temp->next = *pp;
temp->prev = NULL;
if(*pp != NULL)
{
(*pp)->prev = temp;
}
*pp = temp;
}
void ReadStructure(struct Test * p)
{
printf("\nID:");
scanf(" %d", &p->id);
}
void ViewList(Node node)
{
Node temp;
while(node != NULL)
{
temp = node->prev;
if(node->prev == NULL)
{
printf("Prev = NULL\n");
}
else
{
printf("Prev: %d\n", temp->structure.id);
}
printf("Curr: %d\n", node->structure.id);
node = node->next;
}
}
void Delete(Node * head, Node del)
{
if(*head == NULL || del == NULL)
{
return;
}
if(*head == del)
{
*head = del->next;
}
if(del->next != NULL)
{
del->next->prev = del->prev;
}
if(del->prev != NULL)
{
del->prev->next = del->next;
}
free(del);
return;
}
int Menu()
{
int c;
printf("*** M E N U ***\n"
"1 - New Node\n"
"2 - View List\n"
"3 - Delete\n"
"0 - Exit\n"
"\n>> ");
scanf(" %d", &c);
return c;
}
int main()
{
int c;
struct Test test;
Node list = NULL;
Node del = NULL;
do {
c = Menu();
switch (c)
{
case 1: ReadStructure(&test);
NewNode(test, &list); break;
case 2: ViewList(list); break;
case 3: printf("\nElement to Delete: ");
scanf("%d", &del->structure.id);
Delete(&list, del); break;
default: c = 0;
}
} while (c != 0);
return 0;
}
I think the problem is related to the scanf() for the Node del, but i'm not sure. When i just pass list or list->next as second argument to the function Delete() it works. Is everything all right with the code?
int main()
{
...
Node del = NULL;
...
scanf("%d", &del->structure.id);
Your program should crash here. You are dereferencing a null pointer.
Probably you will need to read the user input into a temporary id variable, then search the list for a matching item, and if you find one, then you can try deleting it.
Ok, i added a function that searches for the node to be deleted and i modified a bit the Delete() function, this is the workaround, thank you for the suggestions:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
struct Test
{
int id;
};
typedef struct Node {
struct Test structure;
struct Node * next;
struct Node *prev;
}TNode;
typedef TNode* Node;
void NewNode(struct Test p, Node *pp)
{
Node temp;
temp = (Node)malloc(sizeof(struct Node));
temp->structure = p;
temp->next = *pp;
temp->prev = NULL;
if(*pp != NULL)
{
(*pp)->prev = temp;
}
*pp = temp;
}
void ReadStructure(struct Test * p)
{
printf("\nID:");
scanf(" %d", &p->id);
}
void ViewList(Node node)
{
Node temp;
while(node != NULL)
{
temp = node->prev;
if(node->prev == NULL)
{
printf("Prev = NULL\n");
}
else
{
printf("Prev: %d\n", temp->structure.id);
}
printf("Curr: %d\n", node->structure.id);
node = node->next;
}
}
Node SearchNode(Node head)
{
int d;
printf("\nElement to Delete:");
scanf("%d", &d);
while(head != NULL)
{
if(head->structure.id == d)
{
return head;
}
head = head->next;
}
printf("\nNo Element [%d] Found", d);
return NULL;
}
void Delete(Node * head, struct Test temp)
{
Node del = SearchNode(*head);
if(*head == NULL || del == NULL)
{
return;
}
if(*head == del)
{
*head = del->next;
}
if(del->next != NULL)
{
del->next->prev = del->prev;
}
if(del->prev != NULL)
{
del->prev->next = del->next;
}
free(del);
return;
}
int Menu()
{
int c;
printf("\n*** M E N U ***\n"
"1 - New Node\n"
"2 - View List\n"
"3 - Delete\n"
"0 - Exit\n"
"\n>> ");
scanf(" %d", &c);
return c;
}
int main()
{
int c;
struct Test test, del;
Node list = NULL;
do {
c = Menu();
switch (c)
{
case 1: ReadStructure(&test);
NewNode(test, &list); break;
case 2: ViewList(list); break;
case 3: Delete(&list, del); break;
default: c = 0;
}
} while (c != 0);
return 0;
}
del value is NULL, but you reference it when you delete.
What you need is to search a node in the list for the givent id and then delete it.
So I'm having issue with my code with the structure I'm using. I would like my structure to be able add,retrieve or sort but I'm getting a lot of problem with the structure. It work if I use only number but I need to user 3 string. One for firstname, lastname and phonenumber but I can't figure.
This is the code I'm having right now:
#include <stdio.h>
#include <stdlib.h>
struct node
{
int data;
char first[15];
char last[15];
char phone[12];
struct node *next;
}*head;
void append(int num, char f[15], char l[15],char p[12])
{
struct node *temp, *right;
temp = (struct node *)malloc(sizeof(struct node));
temp->data = num;
strcpy(temp->first, f);
strcpy(temp->last, l);
strcpy(temp->phone, p);
right = (struct node *)head;
while (right->next != NULL)
right = right->next;
right->next = temp;
right = temp;
right->next = NULL;
}
void add(int num, char f[15], char l[15],char p[12])
{
struct node *temp;
temp = (struct node *)malloc(sizeof(struct node));
temp->data = num;
strcpy(temp->first, f);
strcpy(temp->last, l);
strcpy(temp->phone, p);
if (head == NULL)
{
head = temp;
head->next = NULL;
}
else
{
temp->next = head;
head = temp;
}
}
void addafter(int num, char f[15], char l[15],char p[12],int loc)
{
int i;
struct node *temp, *left, *right;
right = head;
for (i = 1; i<loc; i++)
{
left = right;
right = right->next;
}
temp = (struct node *)malloc(sizeof(struct node));
temp->data = num;
strcpy(temp->first, f);
strcpy(temp->last, l);
strcpy(temp->phone, p);
left->next = temp;
left = temp;
left->next = right;
return;
}
void insert(int num, char f[15], char l[15],char p[12])
{
int c = 0;
struct node *temp;
temp = head;
if (temp == NULL)
{
add(num,f,l,p);
}
else
{
while (temp != NULL)
{
if (temp->data<num)
c++;
temp = temp->next;
}
if (c == 0)
add(num,f,l,p);
else if (c<count())
addafter(num,f,l,p, ++c);
else
append(num,f,l,p);
}
}
int delete(int num)
{
struct node *temp, *prev;
temp = head;
while (temp != NULL)
{
if (temp->data == num)
{
if (temp == head)
{
head = temp->next;
free(temp);
return 1;
}
else
{
prev->next = temp->next;
free(temp);
return 1;
}
}
else
{
prev = temp;
temp = temp->next;
}
}
return 0;
}
void display(struct node *r)
{
r = head;
if (r == NULL)
{
return;
}
while (r != NULL)
{
printf("%d ", r->data);
r = r->next;
}
printf("\n");
}
int count()
{
struct node *n;
int c = 0;
n = head;
while (n != NULL)
{
n = n->next;
c++;
}
return c;
}
int main()
{
int i, num;
char fname[15], lname[15], phone[12];
struct node *n;
head = NULL;
while (1)
{
printf("\nList Operations\n");
printf("===============\n");
printf("1.Insert\n");
printf("2.Display\n");
printf("3.Retrieve\n");
printf("4.Delete\n");
printf("5.Exit\n");
printf("Enter your choice : ");
if (scanf("%d", &i) <= 0){
printf("Enter only an Integer\n");
exit(0);
}
else {
switch (i)
{
case 1:
printf("Enter the id, first, last and phone (Separte with space) : ");
scanf("%d %s %s %s", &num,fname,lname,phone);
insert(num,fname,lname,phone);
break;
case 2:
if (head == NULL){
printf("List is Empty\n");
}else{
printf("Element(s) in the list are : ");
}
display(n);
break;
case 3:
//To be made
//scanf("Retrieve this : %d\n", count());
break;
case 4:
if (head == NULL){
printf("List is Empty\n");
}else{
printf("Enter the number to delete : ");
scanf("%d", &num);
if (delete(num))
printf("%d deleted successfully\n", num);
else
printf("%d not found in the list\n", num);
}
break;
case 5:
return 0;
default:
printf("Invalid option\n");
}
}
}
return 0;
}
Thanks for anyone that could explain me the issue and or fix it.
Everywhere you have:
temp->data = num;
add the lines
strcpy(temp->first, f);
strcpy(temp->last, l);
strcpy(temp->phone, p);