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Problem to access members in pointer struct located in another pointer struct


By : Ahmed Imam
Date : September 16 2020, 11:00 AM
like below fixes the issue In C, x[i] is identical to *(x + i). In your case, the type of mystudents[index] is Student, not Student*.
Therefore, either use (mystudents + index)->nom or, more conventionally, mystudents[index].nom.
code :
mystudients[index]._mycursus = calloc(1, sizeof (Cursus));
mystudients[index]._mycursus[0]._notes = calloc(3, sizeof (int));


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Pointer to first element of C struct is the same as pointer to the struct. But not in C#: Interop problem


By : user3572610
Date : March 29 2020, 07:55 AM
fixed the issue. Will look into that further You should declare two overloads of your extern function that take two different ref struct parameters.

How to access the members of a struct within a struct via a double pointer?


By : Tania Vergara
Date : March 29 2020, 07:55 AM
hope this fix your issue As part of a school assignment, I am given a structure with a double pointer to another structure inside it. I will need to be able to access the members of the nested structure within a function, but am having no luck doing so. , In the structure
code :
typedef struct
{
    char* ID;
    char* PassWord;
}Account, *pAccount, **ppAccount;
typedef struct
{
    unsigned int numAccounts;
    ppAccount accounts;
}FleaBay,*pFleaBay;
pFleaBay->accounts = calloc(pFleaBay->numAccounts, sizeof(pAccount));

How to access struct members from pointer


By : user2611308
Date : March 29 2020, 07:55 AM
will help you It's not valid to de-reference a void* pointer. The de-referencing is basically a numerical off-set from the base-pointer. If the compiler does not know what type the pointer is, how can it know the offset amount, nor is it able to decide whether the member reference is actually valid.
In your function it is cast, It looks like there's a stray &.
code :
void sendChannel(void *channel, void *fetchAddress)
{
    struct channel *chan = (struct channel *)channel;

    if( capChannel( chan ) == lenChannel( chan ) )
    {
        chan->qtail->next = head;
    }
}

How do I access the members of a pointer to pointer to struct?


By : Jamal Williams
Date : March 29 2020, 07:55 AM
Hope that helps Let me breakdown your problem.
In main(), Card *deck = NULL; will allocate a pointer to Card and the pointer is pointing to NULL.
code :
void createDeck(Card ** deck)
{
    //deck = malloc(52 * sizeof(Card *)); //deck is a double pointer pointing to memory of type Card* allocated on stack in calling function main().
    if (deck == NULL)
    {
        fprintf(stderr, "Null pointer error\n"); //If calling function passes NULL, it means there is some issue.
        return;
    }
    *deck = NULL; //In more complex functions, if there are other logic before doing malloc(), it it better to reset the variables with default values.

        //allocate memory for each card in deck
    //for (size_t i = 0; i < 52; i++)
    //{
    //    *(deck + i) = malloc(sizeof(Card));
    //}

    *deck = malloc(sizeof(Card)*52); //Allocate for all 52 Cards together
    if(NULL == *deck)
    {
        fprintf(stderr, "malloc failed\n");
        return;
    }

    //In case you want to access a card using deck variable.
    (*deck)[2].suit = hearts;
}

Why can't pointer to pointer, access struct members without a cast?


By : user3318258
Date : March 29 2020, 07:55 AM
around this issue In C++, I was trying to access the struct members through double pointer headref as shown below , This expression
code :
*headref->data
*( headref->data )
( *headref )->data
((Node*)*headref)->data
( /*(Node*)*/ *headref)->data
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