Resize c array of structs to hold another struct

Question

I have a c struct defined as follows:

typedef struct
{
    int data_size;          
    BYTE* data;
} IMAGE;

I have another struct like this

typedef struct
{
    int nimages;
    IMAGE* images;
} IMGARR

I would like to be able to reallocate images to hold another sizeof(IMAGE) structure so I can just keep an array of images with their binary data.

Here is what I've been trying

IMGARR* image_temp = imgarr->images; //store pointer
image_temp = realloc(&image_temp, (imgarr->nimages + 1) * sizeof(IMAGE)); //realloc memory
memcpy(&imgarr->images[imgarr->nimages], &my_new_image, sizeof(IMAGE));

This doesn't seem to work at all. I seem to have become really rusty at c memory allocation. Any help would be awesome!

Your use of types and variable names is a little bit confusing. Is imgarr of type IMGARR*? Is imgarr-images of type IMAGE*? — R Sahu
– R Sahu, Commented Dec 24, 2014 at 3:48
that is pretty confusing I see that now. I think I have fixed my problem, I'll post an update when I'm able to confirm. — bustedware
– bustedware, Commented Dec 24, 2014 at 4:51

Gopi · Accepted Answer · 2014-12-24 08:08:25Z

1

Right way to do this is:

IMGARR* image_temp = realloc(imgarr->images, (n+1) * sizeof(IMAGE)); /* n = New size */
if(image_temp != NULL)
imgarr->images = image_temp;

edited Dec 24, 2014 at 8:08

answered Dec 24, 2014 at 7:44

Gopi

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Comments

Tommy · Accepted Answer · 2014-12-24 03:37:51Z

0

You've not changed what imgarr->images points to. Check image_temp for NULL but if you got the space then reassign ->images before attempting to write to it.

Also, no need for the memcpy. Direct assignments of structs is allowed.

answered Dec 24, 2014 at 3:37

Tommy

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