HP OpenVMS Systems Documentation

HP C

Run-Time Library Reference Manual for OpenVMS Systems

Order Number: BA554-90014

June 2010

This manual describes the functions and macros in the HP C Run-Time Library for OpenVMS systems.

Revision/Update Information: This manual supersedes the HP C Run-Time Library Reference Manual for OpenVMS Systems, Version 8.3

Software Version: OpenVMS Version 8.4 for Integrity servers
OpenVMS Alpha Version 8.4

Hewlett-Packard Company
Palo Alto, California

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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 its contributors.

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Contents

Index

Preface

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 documentation.

Intended Audience

This manual is intended for experienced and novice programmers who need reference information on the functions and macros found in the HP C RTL.

Document Structure

This manual has the following chapters, reference section, and appendixes:

Chapter 1 provides an overview of the HP C RTL.
Chapter 2 discusses the Standard I/O, Terminal I/O, and UNIX I/O functions.
Chapter 3 describes the character, string, and argument-list functions.
Chapter 4 describes the error-handling and signal-handling functions.
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 operating system.
Chapter 10 gives an introduction to the facilities provided in the HP C environment on OpenVMS systems for developing international software.
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.

Reader's Comments

HP welcomes your comments on this manual. Please send your comments or suggestions to:

openvmsdoc@hp.com

How to Order Additional Documentation

For information about how to order additional documentation, see:

http://www.hp.com/go/openvms/doc/order

Conventions Used in this Document

Convention	Meaning
OpenVMS Integrity servers	The variant of the OpenVMS operating system that runs on the Intel Itanium architecture.
OpenVMS systems	Refers to the OpenVMS operating system on all supported platforms, unless otherwise specified.
`[Return]`	The symbol `[Return]` represents a single stroke of the Return key on a terminal.
Ctrl/X	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.
`switch` statement `int` data type `fprintf` function `<stdio.h>` header file	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.
arg1	Italic type indicates a placeholder, such as an argument or parameter name, and the introduction of new terms.
$ `RUN CPROG [Return]`	Interactive examples show user input in boldface type.
float x; . . . 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 example.
option,...	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.
[output-source,...]	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.
sc-specifier ::= `auto` `static` `extern` `register`	In syntax definitions, items appearing on separate lines are mutually exclusive alternatives.
[a\|b]	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 space character.

Platform Labels

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 Itanium processors.

The information in this manual applies to all of these processors, except when specifically labeled as follows:

Label	Explanation
(ALPHA ONLY)	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 8.4

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.

Unicode Support

The C RTL now supports Unicode, UTF-8 encoding for filenames given in UNIX style. For example, the following filename is now allowed:

/disk/mydir/^U65E5^U672C^U8A9E.txt filename

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 feature.

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$FILENAME_ENCODING_UTF8 and DECC$EFS_CHARSET logicals.

Semaphore Support

C RTL supports the following Open Group semaphore control operations in the C RTL:

System V semaphore routines supported:

semctl() 
semget() 
semop() 
ftok()

POSIX semaphore routines supported:

sem_close() 
sem_destroy() 
sem_getvalue() 
sem_init() 
sem_open() 
sem_post() 
sem_timedwait() 
sem_trywait() 
sem_unlink() 
sem_wait()

Note

Applicable to all semaphore routines

When the semaphore APIs, semget and sem_open 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 1024
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 is 1024

DECC$PRINTF_USES_VAX_ROUND Feature Switch

A new feature switch, DECC$PRINTF_USES_VAX_ROUND, has been added to the C RTL.

With this switch set, the F and E format specifiers of printf use VAX rounding rules for programs compiled with IEEE float.

Symbolic Link and POSIX-Compliant Pathname Support Enhancements

OpenVMS Version 8.3

Enhancements have been made to the Open Group-compliant symbolic-link support and POSIX-compliant pathname support provided in OpenVMS Version 8.3.

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