Objasnjenje koda C++

[Cyrus_M]

Molio bih vas ako mi mozete pojasniti samo ovaj dio koda koji se odnosi na "ispis liste naprijed" i "dodavanje clanova u listu" malo imam problema sa pokazivacima. Samo bi htio da mi pokazete sta te dvije funkcije ustvari rade i na koji nacin ovaj program sortira unesene clanove u listi......

PHP kod:

#include <stdio.h> 
#include <string.h>                                          
#include <stdlib.h>
typedef struct lista {
                     unsigned int kljuc;
                     char naziv[20];
                     struct lista *prethodni;
                     struct lista *slijedeci;
                  } LISTA;
unsigned int broj_elemenata(LISTA *pocetak_liste)
          {
               LISTA *p;
               unsigned int br_el=0;
         p = pocetak_liste;
        while(p)
            {
                   ++br_el;
                    p = p->slijedeci;
           }
   return(br_el);
}
void ispis_liste_naprijed(LISTA *pocetak_liste)
              {
                  LISTA *p;
                   p = pocetak_liste;
                   printf("\n");
                    while(p)
                         {
                           printf("%5d->%20s\n",p->kljuc,p->naziv);
                           p = p->slijedeci;
                         }
}


void dodaj_element(LISTA **pocetak_liste, LISTA **kraj_liste, LISTA *novi_element)
                {
                          LISTA *p, *prethodni;
                           p = prethodni = *pocetak_liste;
                            if(p == NULL)
                                   {
                                         novi_element->slijedeci = NULL;
                                         novi_element->prethodni = NULL;
                                         *pocetak_liste = novi_element;
                                         *kraj_liste = novi_element;
                                         return;
                                    }
                            while(p && p->kljuc <=novi_element->kljuc)
                                         {
                                         prethodni = p;
                                         p = p->slijedeci;
                                         }
                           if(p == *pocetak_liste)
                                    {
                                         novi_element->slijedeci = p;
                                         novi_element->prethodni = NULL;
                                         (*pocetak_liste)->prethodni = novi_element;
                                         *pocetak_liste = novi_element;
                                         return;
                                }
                           prethodni->slijedeci = novi_element;
                           novi_element->prethodni = prethodni;
                           novi_element->slijedeci = p;
                        if(novi_element->slijedeci)
                              novi_element->slijedeci->prethodni= novi_element;
                          else
                               *kraj_liste = novi_element;
}
void dodaj_u_listu(LISTA **pocetak_liste,LISTA **kraj_liste)
              {
              LISTA *novi_element;
              unsigned int ucitani_kljuc;
              char ucitani_naziv[20];
                           do
                                {
                                         printf("Upisi kljuc (0 za kraj) :");
                                         scanf("%5d",&ucitani_kljuc);
                                         if(ucitani_kljuc == 0)
                                              break;
                                         printf("Upisi naziv :");
                                         scanf("%s",&ucitani_naziv);
                                         novi_element = (LISTA *) malloc(sizeof(LISTA));
                                         novi_element->kljuc = ucitani_kljuc;
                                         strncpy(novi_element->naziv, ucitani_naziv,20);
                                         dodaj_element(pocetak_liste, kraj_liste,novi_element);
                                } while(1);
}

int main()
              {
                    LISTA *pocetak_liste=NULL, *kraj_liste=NULL;
                    unsigned int upit;
                          for(;;)
                              {
                              printf("\n\nIzaberi\n"
                             "1.Dodavanje elemenata\n"
                             "2.Brisanje elemenata\n"
                             "3.Ispis liste naprijed\n"
                             "4.Ispis liste nazad\n"
                             "0.Kraj\n"
                             " Izbor: ");
                            scanf("%1d",&upit);
                          switch(upit)
                                         {
                                         case 0: exit(0);
                                         break;
                                         case 1: dodaj_u_listu(&pocetak_liste,&kraj_liste);
                                         break;
                                         case 2: brisi_iz_liste(&pocetak_liste, &kraj_liste);
                                         break;
                                         case 3: ispis_liste_naprijed(pocetak_liste);
                                         printf("---ukupno %d elem.---\n",broj_elemenata(pocetak_liste));
                                         break;
                                         case 4: ispis_liste_nazad(kraj_liste);
                                         printf("---ukupno %d elem.---\n",broj_elemenata(pocetak_liste));
                                         break;
                                       }
                            } 


[PDarko]

Lančane liste su mi slaba tačka, ali ovaj program ne radi. Tačnije radi, ali nema kraja (osim ako se ne koristi Task Manager).

for ( ; ; ) je beskonačna petlja.

[Brains]

PDarko kaže:

Lančane liste su mi slaba tačka, ali ovaj program ne radi. Tačnije radi, ali nema kraja (osim ako se ne koristi Task Manager).

for ( ; ; ) je beskonačna petlja.

Nije bas tako... Ima kraj.

case 0: exit(0);

[PDarko]

Brains kaže:

Nije bas tako... Ima kraj.

case 0: exit(0);

U pravu si. Čim sam video for nism gledao dalje.
Inače, to je nestrukturno programiranje i treba ga izbegavati.

[Cyrus_M]

PDarko kaže:

U pravu si. Čim sam video for nism gledao dalje.
Inače, to je nestrukturno programiranje i treba ga izbegavati.

hehehe.... izbjegavati u sirokom luku.... Hvala puno decki, rjesio sam problem

[fingerprint]

I jos nesto : ovo je cist C, a ne C++
Anyway, ostavite temu otvorenom, ako jos neko ima nedoumice sa svojim sourceom, sto ne bi postovao ovde...