Question

Urgent please! This is in C.

I need to write a function that reads a .txt file in using fgets (line by line) and makes a linked list, with each node storing a pointer to a char array that stores one word in the line it reads. A "word" can be alphabetical, numerical, punctuation, blank lines, or \n.

I have a struct:

struct node
{
void *data;
struct node *next;
};

that stores a pointer to an array of chars in memory, and a pointer to the next word in the line.

The function that should do this is passed the file pointer and should return a pointer to the first node in the linked list.

The text I'm using to test this is a sample from Franz Kafka's Metamorphosis, heres a few paragraphs:

One morning, when Gregor Samsa woke from troubled dreams, he found himself transformed in his bed into a horrible vermin. He lay on his armour-like back, and if he lifted his head a little he could see his brown belly, slightly domed and divided by arches into stiff sections. The bedding was hardly able to cover it and seemed ready to slide off any moment. His many legs, pitifully thin compared with the size of the rest of him, waved about helplessly as he looked. "What's happened to me?" he thought. It wasn't a dream. His room, a proper human room although a little too small, lay peacefully between its four familiar walls. A collection of textile samples lay spread out on the table - Samsa was a travelling salesman - and above it there hung a picture that he had recently cut out of an illustrated magazine and housed in a nice, gilded frame. It showed a lady fitted out with a fur hat and fur boa who sat upright, raising a heavy fur muff that covered the whole of her lower arm towards the viewer. Gregor then turned to look out the window at the dull weather. Drops of rain could be heard hitting the pane, which made him feel quite sad. "How about if I sleep a little bit longer and forget all this nonsense", he thought, but that was something he was unable to do because he was used to sleeping on his right, and in his present state couldn't get into that position. However hard he threw himself onto his right, he always rolled back to where he was. He must have tried it a hundred times, shut his eyes so that he wouldn't have to look at the floundering legs, and only stopped when he began to feel a mild, dull pain there that he had never felt before.

Answer 1

Hi. I have answered similar question before. Here is the completed code for this problem. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. Thanks

#include<stdio.h>

#include<stdlib.h>

#include<string.h>

//structure to represent a node

struct node{

                void* data;

                struct node *next;

};

//required method to read words from a file and create a linked list, return the head

//of the list

struct node* txt2words(FILE *fp){

                //initializing two node pointers to NULL

                struct node* head=NULL;

                struct node* current=NULL;

                //a string to read one line at a time

                char line[200];

                //looping as long as a line is successfully read from input file

                while(fgets(line,200,fp)!=NULL){

                                //tokenizing line by white space to split line into separate words

                                char *word=strtok(line, " ");

                                //looping as long as word is not NULL

                                while(word!=NULL){

                                               //checking if head is NULL

                                               if(head==NULL){

                                                               //assigning memory for head pointer

                                                               head=(struct node*) malloc(sizeof(struct node));

                                                               //assigning memory for data field

                                                               head->data=(char*) malloc(sizeof(20*sizeof(char)));

                                                               //copying word to data field

                                                               strcpy(head->data,word);

                                                               //setting next to NULL

                                                               head->next=NULL;

                                                               //setting head as current node

                                                               current=head;

                                               }else{

                                                               //creating a new node, assigning values

                                                               struct node* node=(struct node*) malloc(sizeof(struct node));

                                                               node->data=(char*) malloc(sizeof(20*sizeof(char)));

                                                               strcpy(node->data,word);

                                                               node->next=NULL;

                                                               //setting as next of current node

                                                               current->next=node;

                                                               //setting this as the new current node

                                                               current=node;

                                               }

                                               //getting next word from the line

                                               word=strtok(NULL, " ");

                                }

                               

                }

                //returning a pointer to the head

                return head;

}

//main for testing

int main(){

                //asking and storing the name of input file

                printf("Enter name of input file: ");

                char filename[20];

                scanf("%s",&filename);

                //opening file, printing error if file not found

                FILE* fp=fopen(filename,"r");

                if(fp==NULL){

                                printf("Error! File not found!\n");

                                return 0; //end of program

                }

                //reading text from file storing the head of linked list in a node pointer

                struct node* head=txt2words(fp);

                //closing file

                fclose(fp);

               

                //taking a reference to head node

                struct node* temp=head;

                //looping until temp is null

                while(temp!=NULL){

                                //printing data stored in temp one word per line

                                printf("%s\n", temp->data);

                                //moving to next node

                                temp=temp->next;

                               

                }

                //line break

                printf("\n");

               

                //now before we exit the program ,we need to deallocate the memory allocated for the

                //nodes, otherwise, it will result in memory leaks

                temp=head;

                while(temp!=NULL){

                                //storing next node (if any)

                                struct node* next=temp->next;

                                //deleting node temp

                                free(temp);

                                //restoring next node as new temp

                                temp=next;

                }

                return 0;

}