Simple c array in struct pointer question

Question

i have a two struct like so:
typedef struct {
       uint8_t data[256];
} foo1;
typedef struct {
       uint32_t data_ptr;
} foo2;
foo1 * ctx;
foo2    ply;
if i want to get the pointer to the data array in ctx and assigned to data_ptr would i do it like so:
ply.data_ptr = &(ctx->data);

Answer 1

&(ctx->data) returns a pointer to an array of 256 integers. This type will look something like uint8_t (*data_ptr)[256]. Instead you should do what falconindy suggested above:
ply.data_ptr = ctx->data
To avoid gcc warnings (which you should always avoid), data_ptr needs to be declared the correct type of pointer. Since ctx->data by itself is nothing more than a pointer to an 8-bit wide integer you want (uint8_t *). ((void *) also works)