I'm trying to do something like this
typedef struct _thingy_t
{
int num;
} thingy_t;
void go(int idk)
{
// normally I could just do
thingy_t* ary[idk];
// but I need the array to be global
}
I need an array of pointers to structs of size idk
Is using a 'double pointer' declared outside of the function the best way to go about this? And what about malloc'ing space for the structs?
You can declare as global and then allocate memory inside function.
if you want to allocate memory for array.
void go(int);
thingy_t *data=NULL;
main()
{
//read idk value.
go(idk);
}
void go(int idk)
{
data = malloc(idk * sizeof(thingy_t) );
// when you allocate memory with the help of malloc , That will have scope even after finishing the function.
}
if you want to allocate memory for array of pointers.
thingy_t **data=NULL;
int main()
{
int i,idk=10;
go(idk);
for(i=0;i<10;i++)
{
data[i]->num=i;
printf("%d ",data[i]->num );
}
return 0;
}
void go(int idk)
{
int i=0;
data=malloc(idk *sizeof( thingy_t * ));
for ( i = 0; i<idk ; i++) {
data[i]=malloc(sizeof( thingy_t));
}
}
Don't forgot to free() the memory which is allocated with malloc.
thingy_t **data=NULL; ?? You sure?
thingy_t **data = NULL; was correct, he wants an array of pointers to thingy_t, not an array of thingy_t. It was sizeof(thingy_t) which was wrong, should have been sizeof(thingy_t*), or even better, sizeof(*data).
thingy_t *array = calloc(idk, sizeof(thingy_t));.thingy_t *array; ... void go(int idk){... array = calloc(idk, sizeof(thingy_t)); ...};and 2)thingy_t *go(int idk){... thingy_t *array = calloc(idk, sizeof(thingy_t)); ... return array;};and somewhere else:thingy_t *ar = go(size);