regarding system functions

Hi pigeon7778,
> System function in unix like open,read,write is it necessary to include a header file?
> For sytem functions will it be automatically loaded or some may need header files?

you will need header files ... check the man pages "synopsis" section to determine which files to include

Sunnycoder

they need header files.
See open() example
http://www.qnx.com/developers/docs/qnx_6.1_docs/neutrino/lib_ref/o/open.html

From there, you can find many other function calls.

hongjun

Pigeon7778,

When you #include a header you are not actually including the code it referrs to. Generally, all you are doing is reminding your module of the interface to those functions such as parameter positioning etc. It is the link phase that actually inserts the required code.

Paul

Conclusion: you don't need header-files if you don't want to. They just come in very handy, for the C-compiler needs a definition of an external function before it can be used, in order to do some type-checking. Take your manual and define the systemcalls yourself.

(Should I stick around to wait for the walls coming down on me??)

>>(Should I stick around to wait for the walls coming down on me??)

Yes! You've just deeply confused a budding programmer by suggesting one of the worst programming practices there is. May you forever live in interesting times :)~

Paul

(As the Chinese saying goes...)

Oops, that hurts. Dear Pigeon7778, please use in 100% of your programming the include-files supplied with your compiler or system. We won't confuse you with the reasons why, unless you want to know.

Paul, it's very interesting over here! :)

Or the 'full' version of the (perhaps scottish) curse:

May you live in interesting times and attract the attention of important people and may all your dreams come true.

http://hawk.fab2.albany.edu/sidebar/sidebar.htm

Paul

Thanks a lot everyone.