build a linked list in c

1#include <stdio.h>
2#include <stdlib.h>
3
4struct node 
5{
6    int num;                        //Data of the node
7    struct node *nextptr;           //Address of the next node
8}*stnode;
9
10void createNodeList(int n); // function to create the list
11void displayList();         // function to display the list
12
13int main()
14{
15    int n;
16		printf("\n\n Linked List : To create and display Singly Linked List :\n");
17		printf("-------------------------------------------------------------\n");
18		
19    printf(" Input the number of nodes : ");
20    scanf("%d", &n);
21    createNodeList(n);
22    printf("\n Data entered in the list : \n");
23    displayList();
24    return 0;
25}
26void createNodeList(int n)
27{
28    struct node *fnNode, *tmp;
29    int num, i;
30    stnode = (struct node *)malloc(sizeof(struct node));
31
32    if(stnode == NULL) //check whether the fnnode is NULL and if so no memory allocation
33    {
34        printf(" Memory can not be allocated.");
35    }
36    else
37    {
38// reads data for the node through keyboard
39
40        printf(" Input data for node 1 : ");
41        scanf("%d", &num);
42        stnode->num = num;      
43        stnode->nextptr = NULL; // links the address field to NULL
44        tmp = stnode;
45// Creating n nodes and adding to linked list
46        for(i=2; i<=n; i++)
47        {
48            fnNode = (struct node *)malloc(sizeof(struct node));
49            if(fnNode == NULL)
50            {
51                printf(" Memory can not be allocated.");
52                break;
53            }
54            else
55            {
56                printf(" Input data for node %d : ", i);
57                scanf(" %d", &num);
58 
59                fnNode->num = num;      // links the num field of fnNode with num
60                fnNode->nextptr = NULL; // links the address field of fnNode with NULL
61 
62                tmp->nextptr = fnNode; // links previous node i.e. tmp to the fnNode
63                tmp = tmp->nextptr; 
64            }
65        }
66    }
67}
68void displayList()
69{
70    struct node *tmp;
71    if(stnode == NULL)
72    {
73        printf(" List is empty.");
74    }
75    else
76    {
77        tmp = stnode;
78        while(tmp != NULL)
79        {
80            printf(" Data = %d\n", tmp->num);       // prints the data of current node
81            tmp = tmp->nextptr;                     // advances the position of current node
82        }
83    }
84} 
85
86

1typedef struct node{
2    int value; //this is the value the node stores
3    struct node *next; //this is the node the current node points to. this is how the nodes link
4}node;
5
6node *createNode(int val){
7    node *newNode = malloc(sizeof(node));
8    newNode->value = val;
9    newNode->next = NULL;
10    return newNode;
11}

1#include <stdio.h>
2#include <string.h>
3#include <stdlib.h>
4#include <stdbool.h>
5
6struct node {
7   int data;
8   int key;
9   struct node *next;
10};
11
12struct node *head = NULL;
13struct node *current = NULL;
14
15//display the list
16void printList() {
17   struct node *ptr = head;
18   printf("\n[ ");
19	
20   //start from the beginning
21   while(ptr != NULL) {
22      printf("(%d,%d) ",ptr->key,ptr->data);
23      ptr = ptr->next;
24   }
25	
26   printf(" ]");
27}
28
29//insert link at the first location
30void insertFirst(int key, int data) {
31   //create a link
32   struct node *link = (struct node*) malloc(sizeof(struct node));
33	
34   link->key = key;
35   link->data = data;
36	
37   //point it to old first node
38   link->next = head;
39	
40   //point first to new first node
41   head = link;
42}
43
44//delete first item
45struct node* deleteFirst() {
46
47   //save reference to first link
48   struct node *tempLink = head;
49	
50   //mark next to first link as first 
51   head = head->next;
52	
53   //return the deleted link
54   return tempLink;
55}
56
57//is list empty
58bool isEmpty() {
59   return head == NULL;
60}
61
62int length() {
63   int length = 0;
64   struct node *current;
65	
66   for(current = head; current != NULL; current = current->next) {
67      length++;
68   }
69	
70   return length;
71}
72
73//find a link with given key
74struct node* find(int key) {
75
76   //start from the first link
77   struct node* current = head;
78
79   //if list is empty
80   if(head == NULL) {
81      return NULL;
82   }
83
84   //navigate through list
85   while(current->key != key) {
86	
87      //if it is last node
88      if(current->next == NULL) {
89         return NULL;
90      } else {
91         //go to next link
92         current = current->next;
93      }
94   }      
95	
96   //if data found, return the current Link
97   return current;
98}
99
100//delete a link with given key
101struct node* delete(int key) {
102
103   //start from the first link
104   struct node* current = head;
105   struct node* previous = NULL;
106	
107   //if list is empty
108   if(head == NULL) {
109      return NULL;
110   }
111
112   //navigate through list
113   while(current->key != key) {
114
115      //if it is last node
116      if(current->next == NULL) {
117         return NULL;
118      } else {
119         //store reference to current link
120         previous = current;
121         //move to next link
122         current = current->next;
123      }
124   }
125
126   //found a match, update the link
127   if(current == head) {
128      //change first to point to next link
129      head = head->next;
130   } else {
131      //bypass the current link
132      previous->next = current->next;
133   }    
134	
135   return current;
136}
137
138void sort() {
139
140   int i, j, k, tempKey, tempData;
141   struct node *current;
142   struct node *next;
143	
144   int size = length();
145   k = size ;
146	
147   for ( i = 0 ; i < size - 1 ; i++, k-- ) {
148      current = head;
149      next = head->next;
150		
151      for ( j = 1 ; j < k ; j++ ) {   
152
153         if ( current->data > next->data ) {
154            tempData = current->data;
155            current->data = next->data;
156            next->data = tempData;
157
158            tempKey = current->key;
159            current->key = next->key;
160            next->key = tempKey;
161         }
162			
163         current = current->next;
164         next = next->next;
165      }
166   }   
167}
168
169void reverse(struct node** head_ref) {
170   struct node* prev   = NULL;
171   struct node* current = *head_ref;
172   struct node* next;
173	
174   while (current != NULL) {
175      next  = current->next;
176      current->next = prev;   
177      prev = current;
178      current = next;
179   }
180	
181   *head_ref = prev;
182}
183
184void main() {
185   insertFirst(1,10);
186   insertFirst(2,20);
187   insertFirst(3,30);
188   insertFirst(4,1);
189   insertFirst(5,40);
190   insertFirst(6,56); 
191
192   printf("Original List: "); 
193	
194   //print list
195   printList();
196
197   while(!isEmpty()) {            
198      struct node *temp = deleteFirst();
199      printf("\nDeleted value:");
200      printf("(%d,%d) ",temp->key,temp->data);
201   }  
202	
203   printf("\nList after deleting all items: ");
204   printList();
205   insertFirst(1,10);
206   insertFirst(2,20);
207   insertFirst(3,30);
208   insertFirst(4,1);
209   insertFirst(5,40);
210   insertFirst(6,56);
211   
212   printf("\nRestored List: ");
213   printList();
214   printf("\n");  
215
216   struct node *foundLink = find(4);
217	
218   if(foundLink != NULL) {
219      printf("Element found: ");
220      printf("(%d,%d) ",foundLink->key,foundLink->data);
221      printf("\n");  
222   } else {
223      printf("Element not found.");
224   }
225
226   delete(4);
227   printf("List after deleting an item: ");
228   printList();
229   printf("\n");
230   foundLink = find(4);
231	
232   if(foundLink != NULL) {
233      printf("Element found: ");
234      printf("(%d,%d) ",foundLink->key,foundLink->data);
235      printf("\n");
236   } else {
237      printf("Element not found.");
238   }
239	
240   printf("\n");
241   sort();
242	
243   printf("List after sorting the data: ");
244   printList();
245	
246   reverse(&head);
247   printf("\nList after reversing the data: ");
248   printList();
249}

1node_t *create(int nodes)
2{
3	// code that builds the list
4}