Thread: Singly linked list c

Here's my code I'm trying to figure out how to add stuff to inner list but cant figure out what exactly I'm doing wrong here as I had nothing said about them on my lectures thuz I'm kind of lost about what to do. The function dodajprzedmiot is my attempt at doing so could somebody tell me exactly what I'm doing wrong and correct me or provide example how should it be done?Also would love if somebody could provide link to good lectures about singly linked lists and text/binary files ,Thanks.

Code:

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


typedef struct lista lista;
typedef struct item item;
struct item
{
    char item_name[30];
    item *next;
};
struct lista
{
    int liczba;
    item *data;
    char napis[10];
    lista *next;
};
lista* find(lista *l,char name[61])
{
    lista *current = l;
        int i;
        for(i=1;current!=NULL;i++)
        {
            if(strcmp(current->napis,name) == 0)
            {
                printf("[%d] %d %s\n",i ,current->liczba,current->napis);
                return current;
            }
            current=current->next;
    }
    return (NULL);
}
lista *dodajprzedmiot(lista *temp, char *item_named)
{
      if(temp->data == NULL)
    {
        temp = (lista*)malloc(sizeof(lista));
        strcpy(temp->data->item_name, item_named);
        temp->data->next = NULL;
    }
    else
    {
        lista *pom;
        pom = temp;


        while(pom->data->next) pom->data=pom->data->next;


        pom->next=(lista*)malloc(sizeof(lista));
        strcpy(pom->data->next->item_name, item_named);
        pom->data->next->next=NULL;
    }
    return (NULL);
}
lista* kasuj(lista *list)
{
   lista *pom=NULL;


    while(list)
    {
        pom=list->next;
        free(list);
        list=pom;
    }
    return NULL;
}


void dodaj(lista **l, int n, char tab[100])
{
    if((*l)==NULL)
    {
        *l = (lista*)malloc(sizeof(lista));
        (*l)->liczba=n;
        strcpy((*l)->napis, tab);
        (*l)->next = NULL;
    }
    else
    {
        lista *pom;
        pom=(*l);


        while(pom->next) pom=pom->next;


        pom->next=(lista*)malloc(sizeof(lista));
        pom->next->liczba=n;
        strcpy(pom->next->napis, tab);
        pom->next->next=NULL;
    }
}


void dodajmiejsce(lista **l, int n, char tab[100])
{
    if((*l)==NULL)
    {
        *l = (lista*)malloc(sizeof(lista));
        (*l)->liczba=n;
        strcpy((*l)->napis, tab);
        (*l)->next =NULL;
        return;
    }


    if( n<(*l)->liczba)
    {
        lista *pom=NULL;
        lista *pom2=NULL;


        pom=(lista*)malloc(sizeof(lista));
        pom->liczba=n;
        strcpy(pom->napis, tab);
        pom2=pom;
        pom->next=(*l);
        (*l)=pom2;
        return;
    }
    else
    {
        lista *pom;
        lista *pom2;
        pom=(*l);


        while((pom->next!= NULL) && (n>pom->next->liczba)) pom=pom->next;


        pom2=pom->next;


        pom->next=(lista*)malloc(sizeof(lista));
        pom->next->liczba=n;
        strcpy(pom->next->napis, tab);
        pom->next->next=pom2;
    }
}


void wypiszliste(lista *lis)
{
  for( ; lis; lis=lis->next)
  {
    printf("%d %s \n", lis->liczba, lis->napis);
  }
}


lista* usun(lista *l, int us)
{
    if(l==NULL)
    return l;


    if(l->liczba == us)
    {
        lista *pom=l->next;
        free(l);
        return pom;
    }
    else
    {
        lista *zwrot=l;


         lista *pom=NULL;


        while(( l->next->liczba != us) && (l->next->next!=NULL))  l=l->next;


        if(l->next->liczba==us)
        {
        pom=l->next;


        l->next=l->next->next;
        free(pom);
        }


        return zwrot;
    }
}




int licz(lista* p)
{
int l=0;
for(;p;p=p->next)
l++;
return l;
}




int main()
{
    int wybur, l;
    char ss[100];


    srand(time(0));
    lista *pocz=NULL;


    dodaj(&pocz, 1, "jeden");
    dodaj(&pocz, 2, "dwa");
    dodaj(&pocz, 3, "trzy");
    dodaj(&pocz, 4, "cztery");
    dodaj(&pocz, 5, "piec");
    dodaj(&pocz, 6, "szesc");
    dodaj(&pocz, 7, "siedem");
    dodaj(&pocz, 8, "osiem");
    dodaj(&pocz, 9, "dziewiec");
    while(1)
    {
            wypiszliste(pocz);
            printf("\n\nElementow: %d, \nOPCJE:\n1 dodaj \n 2 usun\n 3 usun wszystkie\n", licz(pocz));
            scanf("%d", &wybur);
            if (wybur==1)
            {
                    printf(" podaj liczbe\n");
                    scanf("%d", &l);
                    printf(" podaj opis\n");
                    scanf("%s", ss);
                    dodajmiejsce(&pocz, l, ss);
            }
            if(wybur==2)
            {
                 printf(" podaj liczbe do usuniecia\n");
                 scanf("%d", &l);
                 pocz=usun(pocz, l);
            }
            if(wybur==3)
            {
                pocz=kasuj(pocz);
             }
             if(wybur==4)
            {
                  char namec[30];
                 printf("podaj imie");
                 scanf("%s",namec);
                 find(pocz,namec);
             }
             if(wybur==5)
                {
                    char nameo[30];
                    char namec[30];
                    lista *temporal = NULL;
                    printf("name of client to add");
                    scanf("%s",namec);
                    printf("name of item");
                    scanf("%s",nameo);
                    temporal = find(pocz,namec);
                    dodajprzedmiot(temporal,nameo);
                }
    }
    return 0;
}

I find your program very difficult to read. It's almost as if it's in another language.

However, in the function you're having trouble with you are mallocing a new list where it seems you should be mallocing a new item. I.e., something like:

Code:

void dodajprzedmiot(lista *temp, char *item_named) {
    if (temp->data == NULL) {
        temp->data = malloc(sizeof(item));
        strcpy(temp->data->item_name, item_named);
        temp->data->next = NULL;
    }else{
        item *pom = temp->data;
        while(pom->data->next)
            pom->data = pom->data->next;
        pom->next = malloc(sizeof(item));
        strcpy(pom->data->next->item_name, item_named);
        pom->data->next->next = NULL;
    }
}

I haven't tested this, but you get the idea.

Also, you should test that malloc actually succeeds before proceeding (it returns NULL if it fails). It's best to make a separate function to malloc, test, and initialize new elements.