pointer to pointer assignment in list

Question

#include <stdio.h> 
#include <stdlib.h>
#define ROZ 100
struct lista
{
    char *imie ;
    char *nazwisko;
    long int data;
    struct wsk * next;
};

int add (struct lista** head)
{
    struct lista *wsk;
    wsk=(struct lista*)malloc(sizeof(struct lista));
    long int data;
    wsk->imie=(char*)malloc(ROZ);
    if(wsk-> imie==NULL)
        return -1;
    wsk->nazwisko=(char*)malloc(ROZ);
    if(wsk->nazwisko==NULL)
        return -2;
    printf("podaj imie");
    fgets(wsk->imie,ROZ,stdin);
    printf("podaj nazwisko");
    fgets(wsk->nazwisko, ROZ, stdin);
    printf("podaj date urodzenia");
    scanf("%ld",&data);
    wsk->data=data;
    wsk->next=(*head);
    (*head)=wsk;
}


main()
{
    struct lista *head, *wsk;
    int a, spr;
    while(a!=4)
    {
        printf("Aby wypisac liste wpisz 1, aby dodac wiersz wpisz 2, aby usunac wiersz wpisz 3, aby zakonczyc prace programu wpisz 4");
        scanf("%d",&a);
        if(a==2)
        {
            spr=add(&head);
            {
                if(spr<0)
                    printf("blad");
            }
        }
    }
}

I don't know how am I suppose to move the head of the list(29 line), program doesn't compile there.

"program doesn't compile there" - If it does not compile,could you include the error(s) and/or warning(s) that you get in your post? — Spikatrix
– Spikatrix, Commented Jan 11, 2015 at 14:16
Perhaps if your program knew what a struct wsk was (which is not what a struct lista is) at least one of your errors would be more obvious. — WhozCraig
– WhozCraig, Commented Jan 11, 2015 at 14:18

Spikatrix · Accepted Answer · 2015-01-11 14:33:43Z

2

struct lista
{
    char *imie ;
    char *nazwisko;
    long int data;
    struct wsk * next;
};

Here,just change the wsk to lista and also add

return 0;

at the end of the function add.

Also,when you enter the while loop for the first time,a isn't initialized and it contains "Garbage values". So,the condition may/may not be true. To fix it,just change the while loop into a do...while loop as this loop executes at least once before the condition is checked.

It is also a good practice to check the return values of scanf,malloc etc to see if they were successful.

answered Jan 11, 2015 at 14:33

Spikatrix

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