Question

Assume that I have a structure as below:

struct line {
       int length;
       char contents[];
};

struct line *thisline = (struct line *) malloc (sizeof (struct line) + this_length);
thisline->length = this_length;

Where is the allocated space for contents? In heap or in the coming address after length?

Answer 1

Both. It’s in the heap, since thisline points to an allocated buffer in the heap. The extra size you’ve requested in the malloc() call serves as the allocated area for thisline->contents. Thus, thisline->contents begins right after thisline->length.