Resizing a char[x] to char[y] at runtime

Question

OK, I hope I explain this one correctly. I have a struct:

typedef struct _MyData
{
   char Data[256];
   int  Index;
} MyData;

Now, I run into

Answer 1

You may be able to do this like this, without allocating a pointer for the array:

typedef struct _MyData
{
    int Index;
    char Data[1];
} MyData;

Later, you allocate like this:

int bcount = 256;
MyData *foo;

foo = (MyData *)malloc(sizeof(*foo) + bcount);

realloc:

int newbcount = 512;
MyData *resized_foo;

resized_foo = realloc((void *)foo, sizeof(*foo) + newbcount);