GCC array type has incomplete element type

Question

I have declared a struct  and I try to pass an array of those structs  as well as a double array of doubles  and an integer  into a function  I get an  array type has incomplete element type  message from gcc when I compile it  What have I got wrong in how I pass the struct into the function   typedef struct graph node     int X    int Y    int active    g node   void print graph g node graph node    double weight      int nodes     I have also tried struct g node graph node    but I get the same thing

User · Answer

The compiler needs to know the size of the second dimension in your two dimensional array   For example   void print graph g node graph node    double weight   5   int nodes

User · Answer

It s the array that s causing trouble in   void print graph g node graph node    double weight      int nodes     The second and subsequent dimensions must be given   void print graph g node graph node    double weight   32   int nodes     Or you can just give a pointer to pointer   void print graph g node graph node    double   weight  int nodes     However  although they look similar  those are very different internally   If you re using C99  you can use variably-qualified arrays   Quoting an example from the C99 standard  section   6 7 5 2 Array Declarators    void fvla int m  int C m  m       valid  VLA with prototype scope  void fvla int m  int C m  m       valid  adjusted to auto pointer to VLA       typedef int VLA m  m          valid  block scope typedef VLA     struct tag           int   y  n                invalid  y not ordinary identifier         int z n                   invalid  z not ordinary identifier            int D m                       valid  auto VLA     static int E m                invalid  static block scope VLA     extern int F m                invalid  F has linkage and is VLA     int   s  m                    valid  auto pointer to VLA     extern int   r  m             invalid  r has linkage and points to VLA     static int   q  m     amp B       valid  q is a static block pointer to VLA       Question in comments           In my main    the variable I am trying to pass into the function is a double array      so how would I pass that into the function  Passing array 0  0  into it gives me incompatible argument type  as does  amp array and  amp array 0  0     In your main    the variable should be   double array 10  20     or something faintly similar  maybe  double array   20        1 0  0 0                  You should be able to pass that with code like this   typedef struct graph node       int X      int Y      int active    g node   void print graph g node graph node    double weight   20   int nodes    int main void        g node g 10       double array 10  20       int n   10       print graph g  array  n       return 0      That compiles  to object code  cleanly with GCC 4 2  i686-apple-darwin11-llvm-gcc-4 2  GCC  4 2 1  Based on Apple Inc  build 5658   LLVM build 2336 9 00   and also with GCC 4 7 0 on Mac OS X 10 7 3 using the command line    usr bin gcc -O3 -g -std c99 -Wall -Wextra -c zzz c

[c] GCC: array type has incomplete element type

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