INTRO(3) DOMAIN/IX Reference Manual (SYS5) INTRO(3)
NAME
intro - introduction to subroutines and libraries
USAGE
#include <stdio.h>
#include <math.h>
DESCRIPTION
This section describes functions found in various libraries,
other than those functions that directly invoke UNIX system
primitives, which are described in Section 2 of this volume.
Certain major collections are identified by a letter after
the section number:
(3C) These functions, together with those of Section 2 and
those marked (3S), constitute the Standard C Library.
Declarations for some of these functions may be
obtained from #include files indicated on the
appropriate pages.
(3S) These functions constitute the ``standard I/O pack-
age'' (see stdio(3S)). Declarations for these func-
tions may be obtained from the #include file
<stdio.h>.
(3M) These functions constitute the Math Library, libm.
Declarations for these functions may be obtained from
the #include file <math.h>. Several generally useful
mathematical constants are also defined there.
(3X) Various specialized libraries. The files in which
these libraries are found are given on the appropriate
pages.
DEFINITIONS
A character is any bit pattern able to fit into a byte on
the machine. The null character is a character with value
zero, represented in the C language as `\0'. A character
array is a sequence of characters. A null-terminated char-
acter array is a sequence of characters, the last of which
is the null character. A string is a designation for a
null-terminated character array. The null string is a
character array containing only the null character. A NULL
pointer is the value that is obtained by casting 0 into a
pointer. The C language guarantees that this value will not
match that of any legitimate pointer, so many functions that
return pointers return zero to indicate an error. NULL is
defined as 0 in <stdio.h>; the user can include an appropri-
ate definition if not using <stdio.h>.
NOTE TO DOMAIN/IX USERS
Because of the global libraries /lib/clib and /lib/unixlib,
the DOMAIN/IX subroutines and libraries don't need to be
bound into the system, but are loaded automatically when the
Printed 5/10/85 INTRO-1
INTRO(3) DOMAIN/IX Reference Manual (SYS5) INTRO(3)
system comes up.
DIAGNOSTICS
Functions in the C and Math Libraries (Sections 3C and 3M)
may return the conventional values 0 or _HUGE (the largest-
magnitude single-precision floating-point numbers; HUGE is
defined in the <math.h> header file) when the function is
undefined for the given arguments or when the value is not
representable. In these cases, the external variable errno
(see intro(2)) is set to the value EDOM or ERANGE.
WARNING
Many of the functions in the libraries call and/or refer to
other functions and external variables described in this
section and in Section 2 (System Calls). If a program inad-
vertantly defines a function or external variable with the
same name, the presumed library version of the function or
external variable may not be loaded. The lint(1) program
checker reports name conflicts of this kind as ``multiple
declarations'' of the names in question. Definitions for
Sections 2, 3C, and 3S are checked automatically. Other
definitions can be included by using the -l option. Use of
lint is highly recommended.
RELATED INFORMATION
intro(2), stdio(3S), ar(1), cc(1), ld(1), lint(1), nm(1)
INTRO-2 Printed 5/10/85