C programming: Dereferencing pointer to incomplete type error

confusedKid picture confusedKid · Apr 5, 2010 · Viewed 221.4k times · Source

I have a struct defined as:

struct {
 char name[32];
 int  size;
 int  start;
 int  popularity;
} stasher_file;

and an array of pointers to those structs:

struct stasher_file *files[TOTAL_STORAGE_SIZE];

In my code, I'm making a pointer to the struct and setting its members, and adding it to the array:

 ...
 struct stasher_file *newFile;
 strncpy(newFile->name, name, 32);
 newFile->size = size;
 newFile->start = first_free;
 newFile->popularity = 0;
 files[num_files] = newFile;
 ...

I'm getting the following error:

error: dereferencing pointer to incomplete type

whenever I try to access the members inside newFile. What am I doing wrong?

Answer

AnT picture AnT · Apr 5, 2010

You haven't defined struct stasher_file by your first definition. What you have defined is an nameless struct type and a variable stasher_file of that type. Since there's no definition for such type as struct stasher_file in your code, the compiler complains about incomplete type.

In order to define struct stasher_file, you should have done it as follows

struct stasher_file {
 char name[32];
 int  size;
 int  start;
 int  popularity;
};

Note where the stasher_file name is placed in the definition.