Uebung 2, ABC einfachverkett

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

typedef struct Element_s {
char songtitle[256], interpreter[256];
struct Element_s *next;
} Element_t;

void getline (char sentence[], int lngth){
char c;
int i=0;
do{
c = getchar();
}while(c=='\n');
while(c!='\n' && i<lngth){
    sentence[i] = c;
    c=getchar();
    i++;

}
}

void readFromKeyboard(Element_t *item){
if(item==0) return;
printf("Unesite ime pjesme: ");
getline(item->songtitle, 255);
printf("Unesite ime pjevaca: ");
getline(item->interpreter, 255);


}

Element_t *allocateElement(){
    Element_t *elem = malloc(sizeof(Element_t));
    if(elem==0){
        printf("Greskaaaa...");
        return 0;
    }
    readFromKeyboard(elem);
    elem->next=0;
    return elem;


}

Element_t *find_End(Element_t *list){
Element_t *end;
if(list==0){
    printf("Prazna lista...");
    return 0;
}
while(list!=0){
        end=list;
list=list->next;

}

return end;
}

Element_t *insertLast(Element_t *list){
Element_t *elem = allocateElement();
Element_t *end;
if(elem ==0){
        printf("Greskaaaa...");
        return 0;

}
if(list!=0){
end=find_End(list);
end->next=elem;
}
else{
    list=elem;
}
return list;
}

Element_t *insertFirst(Element_t *list, Element_t *element){
if(list!=0){
    element->next=list;
    return element;
}
else{
    list=element;
    return element;
}

return element;

}

void freeList(Element_t **list){
Element_t *list2;
list2=*list;
if(list2==0 || list==0){
    printf("Prazna listaa...");
    return ;
}
Element_t *next;
while(list2!=0){
    next=list2->next;
    free(list2);
    list2=next;
}
*list=0;
}

void print_singleElement(Element_t *element){
if(element ==0){
    printf("Prazan element...");
    return;
}
printf("%s ", element->songtitle);
printf("%s \n", element->interpreter);
}

void print_entireList(Element_t *list){
if(list==0){
    printf("Prazna lista...");
    return;
}
int i=1;
while(list!=0){
    printf("%d. ", i);
    print_singleElement(list);
    list=list->next;
    i++;
}
}
long dajVelicinu(Element_t *list){
    if(list==0){
        printf("Prazna listaa...");
        return 0;
    }
    long i=0;
    while(list!=0){
        list=list->next;
        i++;
    }

    return i;
}

void print_list_reverse(Element_t *list){
if(list==0){
    printf("Prazna listaaa...");
    return;
}
if(list->next != 0)
        print_list_reverse(list->next);

    print_singleElement(list);

}

Element_t *get_element(Element_t *list, long index){
    long duzina = dajVelicinu(list);
    if(index>duzina) return 0;
    long i = 1;
    while(list->next != 0){
        if(i==index){
            return list;
        }
        list=list->next;
        i++;
    }
    return 0;
}

void print_list_random(Element_t *list)
{
    long laenge = dajVelicinu(list);
    long feld[laenge];
    int i;
    long repeat = 0;
    long zahl;
    long stelle = 0;

    for(i = 0; i < laenge; i++)
    {
        feld[i] = -1;
    }

    while(stelle < laenge)
    {
        zahl = (rand()%laenge);
        repeat = 0;

        for(i = 0; i < laenge; i++)
        {
            if(zahl == feld[i])
            {
                repeat = 1;
            }
        }

        if(repeat == 0)
        {
            feld[stelle] = zahl;
            stelle++;
        }
    }

    for(i = 0; i < laenge; i++)
    {
        print_singleElement(get_element(list,feld[i]));
    }
}






int main()
{
    /*Element_t *list = 0;
    Element_t *elem = allocateElement();

    int velicina;
    list=insertLast(list);
    list=insertLast(list);
    list=insertLast(list);

    print_entireList(list);
    list=insertFirst(list, elem);
    print_entireList(list);
    printf("Reverse: ");
    print_list_reverse(list);
    printf("Random: ");
    print_list_random(list);

    freeList(&list);*/


    int w = 1;
    Element_t *list=0;
    Element_t *elem = allocateElement();

    while(w!=0){
    printf("Menu:\n");
    printf("1.Dodaj element na kraj: \n");
    printf("2.Dodaj element na pocetak: \n");
    printf("3. Isprintaj listu: \n");
    printf("4. Isprintaj naopako: \n");
    printf("5. Ispintaj random: \n");
    printf("6. Izbrisi listu: \n");
    printf("0. Kraj programa. ");
    scanf("%d", &w);

        switch(w){
    case 1:
        list=insertLast(list);
        break;

    case 2:
        list=insertFirst(list, elem);
        break;

    case 3:
        print_entireList(list);
        break;

    case 4:
        print_list_reverse(list);
        break;
    case 5:
         print_list_random(list);
         break;
    case 6:
        freeList(&list);
        break;
    case 0:
        break;
    default:
    printf("Falsche Eingabe\n");
    break;
        }



    }

    freeList(&list);
    return 0;
}