CODEWITHSUNDEEP
carrayspointersmemorystruct
Astantos
Astantos

Reputation: 121

How to realloc an array of structs

Using c, I'm trying to input stuff into an array of structs, and once that array is filled, double the size of the array and keep going, using realloc.

I know there's been several question like this asked already, but I was hoping someone could explain it clearly since I didn't create my array the way those questions did and am getting a bit confused.

I have a struct

struct Data {
    // Some variables
}

and initialised the array using

struct Data entries[100];
int curEntries = 100;
int counter = 1; // index, I use (counter - 1) when accessing

To realloc, I'm currently using

if(counter == curEntries){  // counter = index of array, curEntries = total
    entries = realloc(entries, curEntries * 2);
}

I know I need to cast realloc to something right? I'm just not sure how or what I'm meant to be casting it to, so I currently don't have anything, which of course gives me the error "assignment to expression with array type"

Thanks!

Upvotes: 1

Views: 3526

Answers (1)

Pras
Pras

Reputation: 4044

struct Data entries[100];// memory is already allocated to this

You need to declare entries as pointer like:

struct Data *entries=NULL;
entries = malloc(curEntries  * sizeof(struct Data));
//When its time to reallocate
entries = realloc(entries, (curEntries * 2 * sizeof(struct Data)));

Upvotes: 3

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