Problem with arrays declared in a structure

tskd · #1 13-May-2008, 21:13

Hi,

I have a structure as part of my code.

CPP / C++ / C Code:


typedef struct CAD {

uint8_t rrc;
uint8_t rd;
// pointers to uint8's in an array
uint8_t *rrgn;
uint8_t *rdi;
uint8_t *rv;
} CAD;

I then try to allocate memory for these arrays and give them predetermined values.

CPP / C++ / C Code:

CAD *c_a_d;
c_a_d->rrc = 0x01;
c_a_d->rd = 0x01;
c_a_d->rrgn = malloc(sizeof(uint8_t) * c_a_d->rrc); /*contains as many array elements as the integer c_a_d->rrc */
c_a_d->rrgn = {0x01};
c_a_d->rdi = malloc(sizeof(uint8_t) * c_a_d->rd);
c_a_d->rdi = {0x01};
c_a_d->rrgn = malloc(sizeof(uint8_t) * c_a_d->rd);
c_a_d->rv = {0x03};

The errors I get are in the 3 assignment statements for the arrays.
THE ERROR EXACTLY IS:
" Expected expression before '{' token"
I have tried reading a lot about this, but no success.

Since I am declaring rrc and rd as 1, all my 3 arrays will have one element only. So, I am taking the liberty to allocate only so much memory and put in a pre-determined value there.

I am on a Fedora 2.6.21-1. Using gcc compiler.
Really appreciate a solution to this.

Thanks!
TS

davekw7x · #2 13-May-2008, 21:34

Quote:

Originally Posted by tskd

I then try to allocate memory for these arrays and give them predetermined values.

CPP / C++ / C Code:

c_a_d->rrgn = {0x01};

c_a_d->rdi = {0x01};

c_a_d->rv = {0x03};

That {}notation can be used for an array initializer list, not in any kind of assignment statement.

For assignment statements. You can use pointer notation:

CPP / C++ / C Code:

    c_a_d->rrgn = malloc(sizeof(uint8_t) * c_a_d->rrc);
    *c_a_d->rrgn = 0x01;

    c_a_d->rdi = malloc(sizeof(uint8_t) * c_a_d->rd);
    *c_a_d->rdi = 0x01;

    c_a_d->rv = malloc(sizeof(uint8_t) * c_a_d->rd);
    *c_a_d->rv = 0x03;

Or you can use index notation

CPP / C++ / C Code:

    c_a_d->rrgn = malloc(sizeof(uint8_t) * c_a_d->rrc);
    c_a_d->rrgn[0] = 0x01;

    c_a_d->rdi = malloc(sizeof(uint8_t) * c_a_d->rd);
    c_a_d->rdi[0] = 0x01;

    c_a_d->rv = malloc(sizeof(uint8_t) * c_a_d->rd);
    c_a_d->rv[0] = 0x03;

Regards,

Dave

tskd · #3 13-May-2008, 21:50

Thanks for the swift reply Dave.
I get the error.

Have a question based on your reply.
So suppose I had my rrc = 2 and rd = 2, how would I initialize my arrays?

*c_a_d->rr = 0x01;
*(c_a_d->rr + 1) = 0x04;

and so on...
Is this the only option? Could I initialize it more intelligently, like in a single statement, without using loops and stuff?
I cannot ask for user input, nor can I input this in a commandline.

Thanks,
TS

davekw7x · #4 13-May-2008, 22:04

Quote:

Originally Posted by tskd

Could I initialize...in a single statement, without using loops and stuff?

No. You can initialize declared arrays with a list in {} braces, but not dynamic "arrays" that use pointers and malloc().

Regards,

Dave

tskd · #5 13-May-2008, 22:09

gotcha

thanks

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