Question

I have these 2 structs:

#define M 100
#define N 100

typedef struct xml_Element {
pData_Element           data;
pAttr_Element           attr_arr[M];
struct xml_Element      *parent;
struct xml_Element      *children[N];
int                     depth;
int                     num_of_children;
int                     num_of_attr;
} Xml_Element,*pXml_Element;

  typedef struct attrElem {
      char *attrName;
      char *attrValue;
   }Attr_Element,*pAttr_Element;

and I wrote this function:

pAttr_Element getXmlAttrArray(pXml_Element node) {
    return node->attr_arr;
}

I have a couple of questions:

1. Why is it illegal? If I change the function to: {pAttr_Element* getXmlAttr....} it works but I don’t understand why.

Inside my struct I have a pointer to an array, where every cell is a pointer of type pAttr_Element right? Or it’s not a pointer to an array? I’m lost 🙁

1. Why is it not working if I change the function to: Attr_Element getXmlAttrArray(..)?
   When I return: node->attr_arr what is the return type?

2. How can I change the struct in order to return a pointer to an array Of pAttr_elements?

Thank you!

Answer 1

The attr_arr field is an array of pAttr_Element, not a pAttr_Element. So you can’t return it as pAttr_Element.
In C, arrays are not pointers, but they decay to pointers in many cases. When you write return node->attr_arr, the array decays to a pointer, which is then returned.

The xml_Element structure doesn’t contain a pointer to the array of pAttr_Element. It actually contains 100 such structures.