Function with realloc crashes program after second run

Question

it seems that after the second time in which the function realocVet runs, the error message "malloc: *** error for object 0x7f8bfac039b0: pointer being realloc'd was not allocated" appears.

void realocVet (float *precoList, char *nomeList, short int *quantidadeList)
{
    static short int p=2,n=100,q=2;
    p=4*p;
    n=4*n;
    q=4*q;
    precoList =realloc(precoList,p * sizeof(float));
    nomeList =realloc(nomeList,n * sizeof(char));
    quantidadeList =realloc(quantidadeList,q * sizeof(short int ));
}

void insertData (float *precoList, char *nomeList, short int *quantidadeList, struct newCard myCard)
{
    static short int slotsAvailable = 2, aux=2,currentCard=0,nnchar=0;
    short int nchar;
    precoList[currentCard] = myCard.preco;
    quantidadeList[currentCard] = myCard.quantidade;
    for (nchar=0;nchar<50;nchar++)
    {
        nomeList[nnchar] = myCard.nome[nchar];
        nnchar++;
    }
    currentCard++;
    slotsAvailable--;

    if (slotsAvailable==0)
    {
        realocVet(precoList, nomeList, quantidadeList);
        slotsAvailable = aux;
        aux = 2*aux;
    }
}

`void realocVet (float *precoList,...` <- The pointer is passed by value, i.e. the function receives a copy. Changes made to the pointer inside the function are not visible in the caller. — Daniel Fischer, May 02 '13 at 18:27

score 4 · Answer 1 · edited May 02 '13 at 18:29

4

You pass in a pointer, float *precoList, which you then realloc (potentially change). Problem is that when you return, the caller still has the old value of the pointer.

When you call the function again, it will be called with the old value that points to free'd memory.

void realocVet (float **precoList, char **nomeList, short int **quantidadeList)
{
    static short int p=2,n=100,q=2;
    p=4*p;
    n=4*n;
    q=4*q;
    *precoList =realloc(*precoList,p * sizeof(float));
    *nomeList =realloc(*nomeList,n * sizeof(char));
    *quantidadeList =realloc(*quantidadeList,q * sizeof(short int ));
}

edited May 02 '13 at 18:29

K Scott Piel

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answered May 02 '13 at 18:27

Joachim Isaksson

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Oh, I get it... It makes sense. How about the call of the function realocVet then? Should I make some change? ps: still not working, but I'm hopeful it will :p – May 02 '13 at 19:43

Function with realloc crashes program after second run

1 Answers1