C: “invalid use of undefined type ‘struct X’ & dereferencing pointer to incomplete type” errors

Question

I\'ve been perusing similar questions to mine for a couple of days but still haven\'t found a solution. Thanks any any help:

I have two files, one containing methods

Answer 1

Move the struct fraction definition to "fraction.h" and

#include "fraction.h"

in both "fraction.c" and "matrix.c"