non-standard header files

[ambika]

Am just a beginner.
Can someone please help me know what do non-standard header files
mean???
I include the header file "conio.h" in my program.I was told that this
is a non-standard header file and was also told that this file is
used for screen manipulations...
-ambika

 

[Martin Dickopp]

Am just a beginner.
Can someone please help me know what do non-standard header files
mean???

A non-standard header is a header not described in the C language standard,
i.e. anything other than

<assert.h> <inttypes.h> <signal.h> <stdlib.h>
<complex.h> <iso646.h> <stdarg.h> <string.h>
<ctype.h> <limits.h> <stdbool.h> <tgmath.h>
<errno.h> <locale.h> <stddef.h> <time.h>
<fenv.h> <math.h> <stdint.h> <wchar.h>
<float.h> <setjmp.h> <stdio.h> <wctype.h>

A conforming C implementation need not have any other header than the ones
listed above.

I include the header file "conio.h" in my program.I was told that this is
a non-standard header file

Correct. Many C implementations don't have it.

and was also told that this file is used for screen manipulations...

Since it is non-standard, there is no telling what its semantics is without
system-specific knowledge. Some systems use it to declare screen
manipulation functions, other systems might use it for other purposes...

(See <http://dspace.dial.pipex.com/town/green/gfd34/art/>, click on
`Software'.)

Martin

 

[Malcolm]

Am just a beginner.
Can someone please help me know what do non-standard header files
mean???
I include the header file "conio.h" in my program.I was told that this
is a non-standard header file and was also told that this file is
used for screen manipulations...

Generally a non-standard header will be used for something which can't be
defined in the same way on all systems. For instance, older computers often
had teletypes rather than screens - printf() works fine but a printat()
function would be impossible to implement.
Sometimes people on the ng give the impression that you shouldn't use
non-standard headers. This is only true if you want the program to be
portable, or if you want help from comp.lang.c on a part of the program that
uses those headers.
If you want blue and green flashing letters dancing all over your screen,
then by all means use conio.h to achieve this.