what is the use of #ifndefs

Stephan Müller fruktopus at gmail.com
Mon Jul 20 12:03:39 EDT 2015

The keyword is 'include guard'


Am 20.07.2015 um 17:55 schrieb leo kirotawa:
> it means you don't want to redefine a .h file
> On Mon, Jul 20, 2015 at 7:03 AM, Ahmed Soliman
> <ahmedsoliman0x666 at gmail.com> wrote:
>> currently I started reading through the linux kernel and I started
>> reading liunx/include/linux/list.h> I understood some of the functions
>> but still I dont know what does these lines of code do
>> #ifndef _LINUX_LIST_H
>> #define _LINUX_LIST_H
>> which exist at the very beginning of the file
>> I also noticed that there is many similar ifndefs in almost any .h
>> file in the kernel
>> note that I understand wnat does ifndef do bu I dont understand what
>> goal is it supposed to achieve at the beginning of the headerfile
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