Include files

Every library function is declared in an include file. Many library functions use symbolic constants and data types, which are defined in include files. The library functions that are implemented as macros are also located in include files.

The include files required for the use of library functions are components of the CRTE library SYSLIB.CRTE. They are stored there as source program elements (type S) and are copied to the program during compilation on the basis of the preprocessor #include directive. The C and C++ User Guides provide a detailed description of how this has to be

<ascii_ebcdic.h>	<assert.h>	<bs2cmd.h>	<cglobals.h>	<cont.h>
<crduc.h>	<ctype.h>	<errno.h>	<float.h>	<ieee_390.h>
<ilcs.h>	<inttypes.h>	<iso646.h>	<limits.h>	<locale.h>
<math.h>	<setjmp.h>	<signal.h>	<stdarg.h>	<stddef.h>
<stdio.h>	<stdlib.h>	<string.h>	<strings.h>	<stxit.h>
<sys.timeb.h>	<sys.types.h>	<time.h>	<timeb.h>	<wchar.h>
<wctype.h>

The following items, among others, may be contained in include files:

• Definitions of symbolic constants with the values required for proper execution of the functions, e.g.:

  BUFSIZ	standard size of the I/O buffer (8192 bytes), as defined by the operating system
  EOF	end-of-file criterion (-1)
  WEOF	end-of-file criterion for wide character files (L“-1“)
  _NFILE	maximum permissible number of concurrently opened files, including the standard files stdin, stdout and stderr (2048).
  NULL	null pointer (0)

• Definitions of data types and structures that are used by the functions, e.g.:

  FILE	Most I/O functions use a pointer to a structure of type FILE (see also section “FILE structure” (Basic terms)”)
  mbstate_t	This data type is used by many of the multibyte functions and corresponds to the type char in this implementation.
  size_t	This data type is used by many of the string functions and corresponds to the type unsigned in this implementation.
  ptrdiff_t	This data type is used for the result of a subtraction of pointers and corresponds to the type int in this implementation.
  wint_t	This data type includes values corresponding to elements of the extended character set and the value WEOF (end of input) and corresponds to the type integer in this implementation.
  wchar_t	This data type is used by the multibyte functions and corresponds to the type long in this implementation.
  wctrans_t	A scalar data type representing locale-specific character translations.
  wctype_t	A scalar data type representing locale-specific character classes; corresponds to the type long in this implementation.
  clock_t	This data type is used by the clock function and corresponds to the type int in this implementation.
  time_t	This data type is used by many of the time functions and corresponds to the type long in this implementation.
  va_list	This data type is used by functions that process variable argument lists (e.g. vprintf).

• The prototype declaration of all functions

  Before a function is called, the data type must be made known, i.e. declared. This is ensured by incorporating the appropriate include file. In the “ANSI” and “STRICT-ANSI” compilation modes, a warning is issued if the declaration is missing. In the “CPLUSPLUS” compilation mode, an error occurs if the declaration is missing, and no module is created.

  See also section “Preprocessor define _STRICT_STDC”.

• The definition of all macros

  Some library functions are implemented as macros. In order to be able to use a macro, the appropriate include file must be incorporated into the program.

The include files contain extern “C” declarations for all functions and data so that C library functions can be called from within C++ sources.

Include file iso646.h

The include file iso646.h contains the following 11 macros, which expand to the adjacent notations and thus serve as alternative notations for the corresponding operators:

and	&&		compl	~		or_eq	|=
and_eq	&=		not	!		xor	^
bitand	&		not_eq	!=		xor_eq	^=
bitor	|		or	| |