Run-Time Library Reference Manual for OpenVMS
This manual describes the functions and macros in the HP C Run-Time
Library for OpenVMS systems.
This manual supersedes the HP C Run-Time Library Reference Manual
for OpenVMS Systems, Version 8.3
OpenVMS Version 8.4 for Integrity servers
OpenVMS Alpha Version 8.4
Palo Alto, California
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The HP OpenVMS documentation set is available on CD-ROM.
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Portions of the HP C Run-Time Library have been implemented
using source copyrighted by the University of California, Berkley and
Copyright (c) 1981 Regents of the University of California.
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This manual describes the HP C Run-Time Library (RTL) for the OpenVMS operating system
on Integrity servers and Alpha. HP OpenVMS Industry Standard 64 for
Integrity servers is the full product name of the OpenVMS operating
system on Intel Itanium processors.
This manual provides reference information about the C RTL functions
and macros that perform input/output (I/O) operations, character and
string manipulation, mathematical operations, error detection,
subprocess creation, system access, screen management, and emulation of
selected UNIX features. It also notes portability concerns between
operating systems, where applicable.
The HP C RTL contains XPG4-compliant internationalization support,
providing functions to help you develop software that can run in
different languages and cultures.
The complete HP C Run-Time Library (C RTL) needed for use with the HP C
and C++ compilers is distributed with the OpenVMS Alpha and OpenVMS
Integrity server operating systems in both shared image and object
module library form.
This manual no longer documents the socket routines used for writing
Internet application programs for the TCP/IP Services protocol. For
help on the socket routines, use the following:
$ HELP TCPIP_Services Programming_Interfaces Sockets_API
Also see the HP TCP/IP Services for OpenVMS product
This manual is intended for experienced and novice programmers who need
reference information on the functions and macros found in the
HP C RTL.
This manual has the following chapters, reference section, and
- Chapter 1 provides an overview of the HP C RTL.
- Chapter 2 discusses the Standard I/O, Terminal I/O, and UNIX I/O
- Chapter 3 describes the character, string, and argument-list
- Chapter 4 describes the error-handling and signal-handling
- Chapter 5 explains the functions used to create subprocesses.
- Chapter 6 describes the Curses Screen Management functions.
- Chapter 7 discusses the math functions.
- Chapter 8 explains the memory allocation functions.
- Chapter 9 describes the functions used to interact with the
- Chapter 10 gives an introduction to the facilities provided in
the HP C environment on OpenVMS systems for developing
- Chapter 11 describes the date/time functions.
- Chapter 12 describes symbolic links and POSIX pathname support.
- The Reference Section describes all the functions in the
HP C RTL.
- Appendix A contains version-dependency tables that list the
HP C RTL functions supported on different OpenVMS versions.
- Appendix B lists the function prototypes that are duplicated in
more than one header file.
The following documents may be useful when programming in HP C
for OpenVMS Systems:
- HP C User's Guide for OpenVMS Systems---For C programmers who need information on using
HP C for OpenVMS Systems.
- HP C Language Reference Manual---Provides language reference information for
HP C on HP systems.
- VAX C to HP C Migration Guide---To help OpenVMS VAX application programmers migrate
from VAX C to HP C.
- HP C Installation Guide for OpenVMS VAX Systems---For OpenVMS system programmers who install the
HP C software on VAX systems.
- HP C Installation Guide for OpenVMS Alpha Systems---For OpenVMS system programmers who install the
HP C software on Alpha systems.
- OpenVMS Master Index---For programmers who need to work
with the VAX and Alpha machine architectures or the OpenVMS system
services. This index lists manuals that cover the individual topics
concerning access to the OpenVMS operating system.
- HP TCP/IP Services for OpenVMS Sockets API and System Services
Programming---For information on the socket routines used for
writing Internet application programs for the HP TCP/IP Services for OpenVMS product or
other implementations of the TCP/IP protocol.
- HP TCP/IP Services for OpenVMS Guide to IPv6---For
information on HP TCP/IP Services for OpenVMS IPv6 features, how to
install and configure IPv6 on your system, changes in the socket
application programming interface (API), and how to port your
applications to run in an IPv6 environment.
- X/Open Portability Guide, Issue 3---Documents what is
commonly known as the XPG3 specification.
- X/Open CAE Specification System Interfaces and Headers, Issue
4---Documents what is commonly known as the XPG4 specification.
- X/Open CAE Specification, System Interfaces and Headers, Issue
4, Version 2---Documents what is commonly known as XPG4 V2.
- X/Open CAE Specification, System Interfaces and Headers, Issue
5---Documents what is commonly known as the XPG5 specification.
- Technical Standard. System Interfaces, Issue 6---Combined
Open Group Technical Standard and IEEE standard. IEEE Std 1003.1-2001,
sometimes known as XPG6.
- Standard for Information Technology - Portable Operating System
Interface (POSIX) - Part 1: System Application Program Interface
(API)---Amendment 2: Threads Extension [C Language]---Documents
what is also known as POSIX 1003.1c-1995.
- ISO/IEC 9945-2:1993 - Information Technology - Portable
Operating System Interface (POSIX) - Part 2: Shell and
Utilities---Documents what is also known as ISO POSIX-2.
- ISO/IEC 9945-1:1990 - Information Technology - Portable
Operating System Interface (POSIX) - Part 1: System Application
Programming Interface (API) (C Language)---Documents what is also
known as ISO POSIX-1.
- ANSI/ISO/IEC 9899:1999 - Programming Languages - C---The
C99 standard, published by ISO in December, 1999 and adopted as an ANSI
standard in April, 2000.
- ISO/IEC 9899:1990-1994 - Programming Languages - C, Amendment
1: Integrity---Documents what is also known as ISO C, Amendment 1.
- ISO/IEC 9899:1990 - Programming Languages -
C---Documents what is also known as ISO C. The normative part is
the same as X3.159-1989, American National Standard for Information
Systems - Programming Language C, also known as ANSI C.
For more information about HP OpenVMS products and services, see:
HP welcomes your comments on this manual. Please send your comments or
How to Order Additional Documentation
For information about how to order additional documentation, see:
Conventions Used in this Document
OpenVMS Integrity servers
The variant of the OpenVMS operating system that runs on the Intel
Refers to the OpenVMS operating system on all supported platforms,
unless otherwise specified.
[Return] represents a single stroke of the Return key on a
The symbol Ctrl/X, where letter X represents a terminal control
character, is generated by holding down the Ctrl key while pressing the
key of the specified terminal character.
Monospace type identifies language keywords and the names of
HP C functions and header files. Monospace type is also used
when referring to a specific variable name used in an example.
Italic type indicates a placeholder, such as an argument or parameter
name, and the introduction of new terms.
Interactive examples show user input in boldface type.
x = 5;
A vertical ellipsis indicates that not all of the text of a program or
program output is illustrated. Only relevant material is shown in the
A horizontal ellipsis indicates that additional parameters, options, or
values can be entered. A comma that precedes the ellipsis indicates
that successive items must be separated by commas.
Square brackets, in function synopses and a few other contexts,
indicate that a syntactic element is optional. Square brackets are not
optional, however, when used to delimit a directory name in an OpenVMS
file specification or when used to delimit the dimensions of a
multidimensional array in HP C source code.
In syntax definitions, items appearing on separate lines are mutually
Brackets surrounding two or more items separated by a vertical bar (|)
indicate a choice; you must choose one of the two syntactic elements.
A delta symbol is used in some contexts to indicate a single ASCII
A platform is a combination of operating system and hardware
that provides a distinct environment. This manual contains information
applicable to the OpenVMS operating system running on VAX, Alpha, and
The information in this manual applies to all of these processors,
except when specifically labeled as follows:
Specific to an Alpha processor.
(INTEGRITY SERVERS ONLY)
Specific to an Intel Itanium processor running the OpenVMS operating
system. On this platform, the product name of the operating system is
OpenVMS Integrity servers.
(INTEGRITY SERVERS, ALPHA)
Specific to Integrity servers and Alpha processors.
New and Changed Features - OpenVMS Version
The following sections describe the C Run-Time Library (C RTL)
enhancements included in OpenVMS Version 8.4. These enhancements
provide improved UNIX portability, standards compliance, and the
flexibility of additional user-controlled feature selections. New C RTL
functions are also included.
The C RTL now supports Unicode, UTF-8 encoding for filenames given in
UNIX style. For example, the following filename is now allowed:
This greatly enhances the UNIX portability of International software
that uses UTF-8 encoded filenames.
A new logical, DECC$FILENAME_ENCODING_UTF8, is provided to enable this
With this logical undefined, the default behavior is to accept
filenames as ASCII and Latin-1 format.
This feature works only on ODS-5 disks. To ENABLE this feature ensure
that you must define both the DECC$FILENAME_ENCODING_UTF8 and
C RTL supports the following Open Group semaphore control operations in
the C RTL:
System V semaphore routines supported:
POSIX semaphore routines supported:
Applicable to all semaphore routines
When the semaphore APIs,
returns an error status value of 28, which indicates 'no space left on
device', you may want to increase the GBLSECTIONS SYSGEN parameter.
Semaphores internally use global sections and having huge number of
semaphore sets on a system may result in exhaustion of GBLSECTIONS. As
a result, the SYSGEN parameter needs to be increased.
Limitations in System V Semaphores
Following are the limitations in System V semaphores:
- Maximum number of System V semaphore sets allowed in a system is
- Maximum number of System V semaphores allowed within a semaphore
set is 1024
- Maximum value of a semaphore is 32767
- Maximum number of System V SEM_UNDO operations allowed in a process
DECC$PRINTF_USES_VAX_ROUND Feature Switch
A new feature switch, DECC$PRINTF_USES_VAX_ROUND, has been added to the
With this switch set, the F and E format specifiers of
use VAX rounding rules for programs compiled with IEEE float.
Symbolic Link and POSIX-Compliant Pathname
OpenVMS Version 8.3
Enhancements have been made to the Open Group-compliant symbolic-link
support and POSIX-compliant pathname support provided in OpenVMS
These enhancements include:
- Support of logical names in POSIX filenames and symlinks
- Loop detection in RMS directory wildcarding
- Following symlinks in RMS directory wildcard searches
- Redesign of on-disk symlink representation
- Miscellaneous bug fixes