c - Error dereferencing pointer to incomplete type and I can't figure out why -

i've went thru material here , can't seem spot error. i've created structs used , when trying manipulate them error. advice appriciated!

these structs defined in kdarray.c

    struct sp_kdarray_t     {         sppoint* points;         int** sorted;         int rows;         int size;     };     struct sp_kdarrays_t     {         spkdarray kdleft;         int leftsize;         int rightsize;         spkdarray kdright;     }; 

and in kdarray.h have:

    typedef struct sp_kdarray_t* spkdarray;     typedef struct sp_kdarrays_t* spkdarrays; 

now when try manipulate them ( recursively building tree ) in following function:

    kdtreenode recursivetreebuild(spkdarray kdarr, int size, sp_tree_split_method spkdtreesplitmethod, int splittingdimension)     {          int split;         kdtreenode result;          result = (kdtreenode)malloc(sizeof(kdtreenode));         if (result == null)         {             sploggerprinterror("memory allocation error", __file__, __func__, __line__);             return null;         }          if (size == 1)         {             result -> dim = -1;             result -> val = -1;             result -> left = null;             result -> right = null;             result -> data = spkdarraycopypoint(kdarr, 0);             if (result -> data == null)             {                 sploggerprinterror("memory allocation error", __file__, __func__, __line__);                 return null;             }         }         else         {             spkdarrays subtrees;              subtrees = spkdarraysplit(kdarr, splittingdimension);             if (subtrees == null)                 return null;              result -> dim = splittingdimension;             result -> val = spkdarraygetmedianvaluebydimension(kdarr, splittingdimension);             result -> data = null;             switch (spkdtreesplitmethod)             {                 case max_spread:                     split = spkdarraygethighestspread(kdarr);                     if (split < 0)                         return null;                     break;                 case random:                     srand(time(null));                     split = rand() % spkdarraygetdimensions(kdarr);                     break;                 case incremental:                     split =  splittingdimension + 1;                     break;             }             result -> left = recursivetreebuild(subtrees -> kdleft, subtrees -> leftsize, spkdtreesplitmethod, split);             result -> right = recursivetreebuild(subtrees -> kdright, subtrees -> rightsize, spkdtreesplitmethod, split);         }          return result;     } 

i "dereferencing error" on :

            result -> left = recursivetreebuild(subtrees -> kdleft, subtrees -> leftsize, spkdtreesplitmethod, split);             result -> right = recursivetreebuild(subtrees -> kdright, subtrees -> rightsize, spkdtreesplitmethod, split); 

thanks in advance!

your error happens because compiler cannot find definition of struct. definition there, in wrong file or in wrong position in file. don't give details on layout of project cannot sure of details...

for example, following code trigger same error:

typedef struct foo_t* foo;  void something1(foo p) {     p->whatever; // error: incomplete type! } struct foo_t // type definition {     int whatever; }; void something2(foo p) {     p->whatever; // ok: type complete } 

so should move definition of structs before function, or maybe header file itself.

or if want structs work opaque types, don't want publicly define them, usual way write public header declarations , private header definitions.