Thread: Delete items in a substructure - Linked List - Two Levels

I am try to delete a sub-struct in a two level linkedlist.


I am able to delete correct if i delete the 1º item, if i delete other items the list don´t work properly.

Code:

typedef struct SPECIES species, *pspecies;
typedef struct ANIMAL no, *pno;
 
struct SPECIES {
    char especie[MAX];
    char idalphanumeric[MAX]; 
    long int nranimais; 
    pno listadeanimais;
    pspecies prox;
};
 
struct ANIMAL {
    char especie[MAX];
    int id;
    char nome[MAX]; 
    int peso;
    char nomelocal[MAX]; 
    pno prox; 
};


pspecies apaga_animal_zoo(pspecies list) {


    pno aux, anterior;


    int i = 1380;


    while (list != NULL) {
        aux = list->listadeanimais;
        anterior = NULL;
        while (aux != NULL) {
            if (aux->id == i) {


                if (anterior == NULL) { // Se for o primeiro animal, vou passar a cabeça da lista para o nó a seguir
                    list->listadeanimais = aux->prox;
                    return list;
                } else {// Não sendo o animal da lista vou ligar o nó "n-1" ao nó "n+1", apagando o nó "n"
                    anterior->prox = aux->prox;
                     list->listadeanimais = aux->prox;
                }


                printf("The Animal with the name %s was remove\n", aux->nome);
               


                free(aux);
                return list;


                //aux = aux->prox;
            } else {
                anterior = aux;
                aux = aux->prox;
            }


        }
        list = list->prox;
    }


    if (aux == NULL) { // The Animal don´t existe.
        puts("Animal nao existe sera enviado para o MENU");
        return list;
    }




    puts("The List is empty");


    return list;
}

> Record and Reading from a Binary File - LinkedList - Two Levels
Well you've still got the messy typedef's

> typedef struct SPECIES species, *pspecies;
> typedef struct ANIMAL no, *pno;
At least species is somewhat related, but how the hell does 'no' relate to ANIMAL.

Code:

struct ANIMAL;

typedef struct SPECIES {
    char especie[MAX];
    char idalphanumeric[MAX]; 
    long int nranimais; 
    struct ANIMAL *listadeanimais;
    struct SPECIES *prox;
} species;
  
typedef struct ANIMAL {
    char especie[MAX];
    int id;
    char nome[MAX]; 
    int peso;
    char nomelocal[MAX]; 
    struct ANIMAL *prox; 
} animal;
 
 
species * apaga_animal_zoo(species * list) {
    animal *aux, *anterior;
 
    int i = 1380;
 
    while (list != NULL) {
        aux = list->listadeanimais;
        anterior = NULL;
        while (aux != NULL) {
            if (aux->id == i) {
                if (anterior == NULL) { // Se for o primeiro animal, vou passar a cabeça da lista para o nó a seguir
                    list->listadeanimais = aux->prox;
                    //!! This misses the 'print and free'
                    return list;
                } else {// Não sendo o animal da lista vou ligar o nó "n-1" ao nó "n+1", apagando o nó "n"
                    anterior->prox = aux->prox;
                    //!! This causes all the animals up to this point to be lost!  Delete this line
                    list->listadeanimais = aux->prox;
                }
 
                printf("The Animal with the name %s was remove\n", aux->nome);
                //!! what about list->nranimais ?
                free(aux);
                return list;
                //aux = aux->prox;
            } else {
                anterior = aux;
                aux = aux->prox;
            }
        }
        list = list->prox;
    }
 
 
    if (aux == NULL) { // The Animal don´t existe.
        puts("Animal nao existe sera enviado para o MENU");
        return list;
    }
 
    puts("The List is empty");
 
    return list;
}

Read the //!! comments.

Something is missing.

Even now if the animal doesn´t exist and i return "list" it came empty when i try to print with again.

Code:

species * apaga_animal_zoo(species * list) {
   
    no  *aux, *anterior;
    
    int i = 1620;


    while (list != NULL) {
        aux = list->listadeanimais;
        anterior = NULL;
        while (aux != NULL) {
            if (aux->id == i) {
                if (anterior == NULL) { // Se for o primeiro animal, vou passar a cabeça da lista para o nó a seguir
                    list->listadeanimais = aux->prox;
                } else {// Não sendo o animal da lista vou ligar o nó "n-1" ao nó "n+1", apagando o nó "n"
                    anterior->prox = aux->prox;
                    //   list->listadeanimais = aux->prox;
                }


                printf("The Animal with the name %s was remove\n", aux->nome);
                list->nranimais = (list->nranimais - 1);
                free(aux);
                return list;
            }
            anterior = aux;
            aux = aux->prox;
        }
        list = list->prox;
    }


    if (aux == NULL) { // The Animal does not exists.
        puts("Animal does not exist you are going to the MAIN MENU");
        return list;
    }


    puts("The List is empty");


    return list;
}

Why do you have 'return list' all over the place when you've messed up the list with
list = list->prox;

You need to sort out your return list statements, since you're now potentially returning a new head to your species list.

A few minor tweaks between lines 36 and 43.