In C, how can i read data from a text file and insert them an linked list that organised in an ascending order according to the first names?

Question

The text file "mh.txt" includes the following names, surnames, gender and birth date of 3 people separated by semicolons.

which look like this:

Tiffany;Evans Smith;F;22/01/1989;

Alex;Williams;M;23/06/1988;

Clay;Bristol;F;30/12/1989;

I want to store every person's details in a node so we'd have 3 nodes in total. All connected in a linked list. Then I want to print the linked list using a print function.

The problem is that my compiler displays the message "fix.exe has stopped working" every time I compile and run! my c file is called fix.c

This is my attempt:

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


#define FALSE 0
#define TRUE 1

#define SIZE 100

struct Node{

    char  fname[SIZE];
    char sname[SIZE];
    char gender;
    char Byear[SIZE];
    struct Node *next;
};

struct ListRecord
{
    struct Node *head;
    struct Node *tail;
    int size;
};
typedef struct ListRecord List;

List* CreateList(void);
void MakeEmptyList(List *);
void printFriends(List *);
List * initialiseFL(List *);

int main(){

    List *myList;
    int option;
    int exit=FALSE;
    char fname[SIZE];

    myList = CreateList();

    myList=initialiseFL(myList);//reads data from text file and adds nodes 
to linked list




    while(!exit){

        fflush(stdin);
        printf("C:>FriendBook friends.txt\n");
        printf("Your FriendBook has been created.\n");
        printf("(1) Insert a new friend\n");
        printf("(2) Print your friends\n");
        printf("(3) Search for your friend\n");
        printf("(4) Block your friend\n");
        printf("(5) Print your blocked friend\n");
        printf("(6) Exit\n");
        printf("Enter your option:");
        printf("\n\n");
        scanf("%d",&option);
        fflush(stdin);

        switch(option){

            case 2:
                printFriends(myList);
                break;

            default:
                printf("Command not recognised!!\n");
                break;

        }
    }


    return 0;
}


List* CreateList(){

    List *l;

    l = (struct ListRecord *) malloc(sizeof(struct ListRecord));
    if (l == NULL)
        printf("Out of memory!\n");

    MakeEmptyList(l);

    return l;
 }

void MakeEmptyList(List *l)
{
    l->head = (struct Node *) malloc(sizeof(struct Node));
    if (l->head == NULL)
        printf("Out of memory!\n");

    l->head->next = NULL;
    l->tail = l->head;
    l->size = 0;
}
List* initialiseFL(List *l){


    FILE *IN;

    IN =fopen("mh.txt", "r");

    if (IN == NULL){
        printf("Could not open text file!!\n");
    }

    while((fgetc(IN))!=EOF){

        struct Node *p;
        p=(struct Node*) malloc(sizeof(struct Node));

        char temp;
        temp=fgetc(IN);

        int i=0;

        //read first name a char at a time until ;
        while(temp!=';'){

            p->fname[i]=temp;
            i++;
            temp=fgetc(IN);
         }
         p->fname[i]='\0';


         //read second name a char at a time until ;
         temp=fgetc(IN);    
         i=0;   
         while(temp!=';'){

             p->sname[i]=temp;
             i++;
             temp=fgetc(IN);
         }
         p->sname[i]='\0';


         //read gender from text file
         temp=fgetc(IN);    
         p->gender=temp;

         //read birth year from text file
         temp=fgetc(IN);    
         temp=fgetc(IN);    
         i=0;   
         while(temp!=';'){

            p->Byear[i]=temp;
            i++;
            temp=fgetc(IN);
        }
        p->Byear[i]='\0';



        //if list is empty, add node right after the dummy
        if (l->size==0){
            l->head->next=p;
            l->tail=p;
            l->size++;
        }

         //if the list contanins one node after the dummy
         struct Node *first;
         first=l->head->next;
         if(l->size==1){
            if(strcmp(p->fname[0],first->fname[0])>0 && first->next==NULL){
                p->next=NULL;
                first->next=p;
                l->tail=p;
                l->size++;
            }
            else{
                 p->next=first;
                 l->head->next=p;
                 l->size++;
                 first=l->head->next;//reset "first" to point to the 1st 
node in the list
            }
         }


         struct Node *second;
         second=first->next;

         //if it is to be added at the beginning 
        if(l->size>=2){
            if(strcmp(p->fname[0],first->fname[0])<0){
                p->next=first;
                l->head->next=p;
                l->size++;
                first=l->head->next;//reset "first" to point to the 1st node 
in the list
             }

             else{
                while(!(strcmp(p->fname,first->fname)>0 && strcmp(p-
>fname,second->fname)<0 )){
                    first=first->next;
                    second=second->next;
                }
                if(second->next==NULL){
                    p->next=NULL;
                    first->next=p;
                }
                else{
                    p->next=second;
                    first->next=p;
                }

                first=l->head->next;//reset "first" to point to the 1st node 
in the list
                second=first->next;//reset "second" to point to the 2st node 
in the list
                }



        }

        }
    fclose(IN);


    return l;
}

 void printFriends(List *l){


    //make a temp head that points to the dummy
    struct Node *temp;
    temp=(struct Node*) malloc(sizeof(struct Node));
    temp=l->head->next;

    printf("Your friends are listed below.\n");
    printf("Name\tSurname\tGender\tBirth Year\n");


     while(temp!=NULL){
         printf("%s\t%s\t%c\t%s\n",temp->fname,temp->sname,temp-
>gender,temp->Byear);
        temp=temp->next;
    }

}

Answer 1

consider one of the statement of your code

if(strcmp(p->fname[0],first->fname[0])<0){

strcmp() excepts both arguments as strings , but p->fname[0] will result in single character , just modify as below.

  if(strcmp(p->fname,first->fname)<0){

And there is bug in below code, you are updating first & second not p thats why loop is running infinitely.

while(!(strcmp(p->fname,first->fname)>0 && strcmp(p->fname,second->fname)<0 )){

    first=first->next;
    second=second->next;
                                }

I hope it will helps.

Answer 2

You can use the code below for your requirement.

What is char Byear[SIZE]; this field? As per your data file, it should be a date field and as forth field in data file is a date.

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

    struct Friend
    {
            char  *name;
            char  *sur;
            char  *gen;
            char  *date;
            struct Friend *next;
    };

    struct Friend * initializeFL(char *);
    void printFriends(struct Friend *);

    int main()
    {
            printf("\nsdasda\n");
            struct Friend *head;
            char fname[100];
            printf("Enter the name of file .txt:  \t");
            gets(fname);
            head=initializeFL(fname);
            printFriends(head);
    }

    struct Friend * initializeFL(char *fname)
    {
            FILE* fpointer;
            char ch;
            fpointer = fopen(fname,"r");
            if(fpointer == NULL)
            {

                do
                {
                    printf("\nFile not found, please enter the name of file again: \t");
                    gets(fname);
                    fpointer = fopen(fname,"r");
                }while(fpointer == NULL);
            }

            //FILE IS OPENED
            struct Friend *head=NULL;
            struct Friend *t, *p, *q;
            char line[255];
            char sent[2]=";";

            while(!feof(fpointer) && fgets(line,sizeof line,fpointer))
            {
                char *name=strtok(line,sent);
                char *sur=strtok(NULL,sent);
                char *gen=strtok(NULL,sent);
                char *date=strtok(NULL,sent);
                    if(head == NULL)
                    {
                              head=(struct Friend*)malloc(sizeof(struct Friend));
                              t = head;
                              t->name = (char *)malloc(strlen(name));
                              t->sur = (char *)malloc(strlen(sur));
                              t->gen = (char *)malloc(strlen(gen));
                              t->date = (char *)malloc(strlen(date));
                              strcpy(t->name,name);
                              strcpy(t->sur,sur);
                              strcpy(t->gen,gen);
                              strcpy(t->date,date);
                              t->next=NULL;
                    }
                    else
                    {
                            p=(struct Friend*)malloc(sizeof(struct Friend));
                            p->name = (char *)malloc(strlen(name));
                            p->sur = (char *)malloc(strlen(sur));
                            p->gen = (char *)malloc(strlen(gen));
                            p->date = (char *)malloc(strlen(date));
                            strcpy(p->name,name);
                            strcpy(p->sur,sur);
                            strcpy(p->gen,gen);
                            strcpy(p->date,date);
                            p->next=NULL;
                            q = t = head;
                            int i = strcmp(p->name,t->name);
                            printf("i = %d\n",i);
                            while(t!=NULL && strcmp(p->name,t->name)> 0)
                            {
                              q = t;
                              t=t->next;
                            }
                            if(t == head)
                            {
                              p->next=head;
                              head=p;
                            }
                            else
                            {
                              q->next = p;
                              p->next = t;
                            }
                     }
            }
            return head;
    }

    void printFriends(struct Friend *head)
    {
            while(head!=NULL)
            {
                    printf("Name :%s\n",head->name);
                    printf("Surname :%s\n",head->sur);
                    printf("Name :%s\n",head->gen);
                    printf("Name :%s\n",head->date);
                    head=head->next;
            }
    }