Inluding functions in header file

Inluding functions in header file

I have header file:
dictionary.h:
#ifndef dictionary_h__
#define dictionary_h__
extern char *BoyerMoore_positive(char *string, int strLength);
extern char *BoyerMoore_negative(char *string, int strLength);
extern char *BoyerMoore_skip(char *string, int strLength);