Dereferencing Pointer to incomplete type

Question

I've been at this for a couple hours and can't figure out this probably stupid mistake. Here are the errors:

crawler.c:8: error: dereferencing pointer to incomplete type

crawler.c:9: error: dereferencing pointer to incomplete type

crawler.c:10: warning: return from incompatible pointer type

The code is:

//--------------------------Header File----------------------------------//
#ifndef CRAWLER_H 
#define CRAWLER_H
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "indexPage.h"
struct pointersWordControl{
    queryHelper **queryArray;
    char** URLs;
};
typedef struct pointersWordControl queryHelperExt;
queryHelperExt  *crawler(const char* FILE_NAME, const int MAX_N);
#endif  

//---------------------------------Crawler.c-------------------------------//
queryHelperExt *crawler(const char* FILE_NAME, const int Max_N)
{

    queryHelper **structArray = malloc(sizeof(struct wordControl*)*50); 
    char** urlString;
    urlString= missionControl(FILE_NAME, Max_N, structArray);
    struct queryHelperExt *queryPass=malloc(sizeof(struct pointersWordControl)*1);
    queryPass->queryArray=structArray;
    queryPass->URLs=urlString; 
    return queryPass;
}

Answer 1

Change

struct queryHelperExt *queryPass=malloc(sizeof(struct pointersWordControl)*1);

to

queryHelperExt *queryPass=malloc(sizeof(struct pointersWordControl)*1);

There is no struct queryHelperExt - the identifier queryHelperExt is a typedef for struct pointersWordControl and doesn't need the struct keywork.

Answer 2

Your problem is that you're declaring queryPass to be of type struct queryHelperExt which is different from the intended type of queryHelperExt . In C, adding the struct keyword makes it a different type (unlike C++).