Linked List Implementation in C




#include <stdio.h>
#include <stdlib.h>

struct node {
    int value;
    struct node* next;
};

void display( struct node** head);
void appendNode( struct node** node1, int val);
void addAtBeginning( struct node** head, int val);
int listLength( struct node** head);
void addNodeAtLocation( struct node** head, int loc, int val);
void reverseList( struct node** head);

int main(){

struct node* head ;
head = NULL ;

//clrscr();

appendNode( &head, 1);
appendNode( &head, 2);
appendNode( &head, 3);
appendNode( &head, 4);
appendNode( &head, 5);
appendNode( &head, 6);

printf("The length of the list is %d \n", listLength(&head) );

display( &head);

reverseList( &head);

display( &head);

printf("The node at 1st is %d \n",getNodeAtLocation( &head, 1));
printf("The node at 2nd is %d \n",getNodeAtLocation( &head, 2));
printf("The node at 3rd is %d \n",getNodeAtLocation( &head, 3));
printf("The node at 4th is %d \n",getNodeAtLocation( &head, 4));

addNodeAtLocation( &head, 3, 400);
addNodeAtLocation( &head, 5, 500);

addAtBeginning( &head, 100);
addAtBeginning( &head, 200);

printf("The node at 1st is %d \n",getNodeAtLocation( &head, 1));
printf("The node at 2nd is %d \n",getNodeAtLocation( &head, 2));
printf("The node at 3rd is %d \n",getNodeAtLocation( &head, 3));
printf("The node at 4th is %d \n",getNodeAtLocation( &head, 4));

addNodeAtLocation( &head, 3, 400);
addNodeAtLocation( &head, 5, 500);

printf("The length of the list is %d\n", listLength(&head) );
display( &head);

return 0;
}

int getNodeAtLocation(struct node** head, int loc){
    struct node* temp;
    temp = *head;
    int i ;
    for( i = 1; i < loc ; i++){
        temp = temp->next;
    }

    return temp->value;
}

void addNodeAtLocation( struct node** head, int loc, int val){
    struct node *temp, *temp1;
    temp = *head;
    int i ;
    for( i = 1; i < loc ; i++){
        temp = temp->next;
    }


    temp1 = (struct node*)malloc(sizeof(struct node));
    temp1->value = val;
    temp1->next = temp->next;
    temp->next = temp1;

}

void addAtBeginning( struct node** head, int val){

    struct node* temp;
    temp = (struct node*)malloc(sizeof(struct node));
    temp->next = *head;
    temp->value = val;
    *head = temp;

}

void display( struct node** head){

    struct node* temp ;

    if( *head == NULL){
        printf("The linked list is empty \n");
    }

    temp = *head;

    while( temp != NULL){
        printf("The value is %d\n", temp->value );
        temp = temp->next;
    }

}

void appendNode( struct node** node1, int val){

    struct node* temp;
    struct node* temp1;

    if( *node1 == NULL){
        temp = (struct node*)malloc(sizeof(struct node));
        temp->value = val;
        temp->next = NULL;
        *node1 = temp;
    } else {
        temp1 = *node1;
        while( temp1->next != NULL){
            temp1 = temp1->next;
        }
        temp = (struct node*)malloc(sizeof(struct node));
        temp->value = val;
        temp->next = NULL;
        temp1->next = temp;

    }

}

int listLength( struct node** head){

    struct node* temp;
    temp = *head ;
    int length = 0;

    if(*head == NULL){
        return length;
    } else {
       while( temp != NULL){
            length++;
            temp = temp->next;
       }
       return length;
    }

}

void reverseList( struct node** head){
    struct node *temp, *temp2, *temp3;
    temp = *head;
    temp3 = NULL;

    if( temp == NULL || listLength(head) == 1 ){
       return;
    }

    while( temp != NULL){
        temp2 = temp->next;
        temp->next = temp3;
        temp3 = temp;
        temp = temp2;
    }

    *head = temp3;
}