CODEWITHSUNDEEP
cmalloc
Cris Barbosa
Cris Barbosa

Reputation: 9

Malloc execution error

I made this method for a test and for some reason the malloc is not working. When I comment it it does work, but otherwise it will just say the program has stopped working.

typedef struct {
    int NroUSP; // chave primária
    int curso;
    int estado;
    int idade;
    bool valido; // para exclusão lógica
} REGISTRO;

typedef struct s {
    int NroUSP; // chave primária
    int curso;
    int estado;
    int idade;
    bool valido;
    struct s* prox;
} NO;

typedef struct {
    NO* inicio;
} LISTA;

These are the structures I used ^

EDIT: THE PROBLEM WAS THIS ASTERISK RIGHT BEFORE AUX

void ex6(){
    REGISTRO* aux;
    FILE *arq = fopen("C:\\Users\\jujuc_000\\Desktop\\Teste\\dados.bin","rb");
    FILE *arq2 = fopen("C:\\Users\\jujuc_000\\Desktop\\Teste\\ex6.bin","wb");
    LISTA l;
    l.inicio = NULL;
    NO*p = (NO*)malloc(sizeof(NO)); // this is the test malloc
    if(arq){
        while(1==fread(&aux,sizeof(REGISTRO),1,arq)){
            /*p = (NO*)malloc(sizeof(NO)); // this is the one I want to keep
            p->NroUSP = aux->NroUSP;
            p->curso = aux->curso;
            p->estado = aux->estado;
            p->idade = aux->idade;
            p->valido = aux->valido;
            if(!l.inicio){
                l.inicio = p;
            }
            p=p->prox;*/
        }
    }

    fclose(arq);
    fclose(arq2);
}

Upvotes: 0

Views: 66

Answers (2)

iammowgli
iammowgli

Reputation: 157

Try the following:

  1. Use feof() instead of if(arq) ...
  2. Set p->prox = NULL;
  3. Either declare 'REGISTRO aux' or allocate memory to 'aux' if declaring it as a pointer.

Upvotes: 0

Ken Y-N
Ken Y-N

Reputation: 15009

fread(&aux,sizeof(REGISTRO),1,arq) is most likely your problem; aux is a pointer to a REGISTRO, but you try to read in a full REGISTRO into it, which more than likely overwrites memory, causing the apparent malloc failure in the next line. Change the declaration to:

REGISTRO aux;

And things should work.

Upvotes: 1

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