Solution:
The issue is with this code:
parent.left = &a;
parent.right = &b;
This is getting pointers to local variables, which will be reinitialized next time on all direction the loop. CharCountNode will al last attempt to delete these objects, however they haven't been allocated by new.
You require to make left and right point to objects allocated on the heap, as that is what CharCountNode is expecting. Something like:
parent.left = new CharCountNode(a);
parent.right = new CharCountNode(b);
You require to include this to just earlier on return dataReturn; in your dataTest function:
dataReturn[i] = NULL ;
Else your while (data[i]) {} will continue further than wanted.
And instead of:
dataReturn[i] = malloc( sizeof(char) * (strlen(*str)) );
write:
dataReturn[i] = malloc(strlen(*str) + 1);
With a view to allocating space for the terminating zero.
BTW sizeof (char) is always 1.
python 3.6 malloc: pointer being freed was not allocated / set a breakpoint in malloc_error_break to debug Abort trap: 6
