Header search paths with gcc using C_INCLUDE_PATH

i'm confused about the following include files(with GCC)

i've A.c and B.c in folder AAA

and B.h in folder BBB

in A.c:

#include <stdio.h>#include "B.h"main(){    errPrint();}

in B.c:

#include <stdio.h>#include "B.h"void errPrint(void)   {    printf("err info\n");}

in B.h:

#ifndef _B_H#define _B_Hvoid errPrint(void);#endif

now i run the command:

#gcc -I /BBB A.c B.c -o exeobj

it's OK.but it seems a little boring that i have to use "-I" to specify header when in other folder.so i edit my "/etc/profile" file and added

C_INCLUDE_PATH=/BBB  export C_INCLUDE_PATH

to specify the header folder, then

echo $C_INCLUDE_PATH

it shows the right route.but when i compile:

#gcc -c A.c B.c

error shows:

error: B.h: No such file or directory

i don't know where went wrong, anybody have clues about it, any suggestions are weclome.

note: i'm a newbie and can't use Makefile yet...