Compaq BASIC for OpenVMS Alpha and VAX Systems

Compaq BASIC for OpenVMS
Alpha and VAX Systems

Reference Manual

Order Number: AA--HY16E--TK

April 2000

This manual provides reference, syntax, and language element information for Compaq BASIC.

Revision/Update Information: This revised manual supersedes the DEC BASIC and VAX BASIC for OpenVMS Systems Reference Manual.

Software Version: Compaq BASIC Version 1.4
for OpenVMS Alpha Systems
Compaq BASIC Version 3.8
for OpenVMS VAX Systems

Operating System and Version: OpenVMS Alpha Version 7.1 or higher
(with IEEE floating-point support);
OpenVMS Alpha Version 6.1 or higher
(without IEEE floating-point support); or
OpenVMS VAX Version 5.5-2 or higher

Compaq Computer Corporation
Houston, Texas

COMPAQ, VAX, VMS, the Compaq logo, and the DIGITAL logo Registered in U.S. Patent and Trademark Office.

Alpha, DEC BASIC, OpenVMS, and VAX BASIC are trademarks of Compaq Information Technologies Group, L.P.

All other product names mentioned herein may be the trademarks or registered trademarks of their respective companies.

Confidential computer software. Valid license from Compaq or authorized sublicensor required for possession, use, or copying. Consistent with FAR 12.211 and 12.212, Commercial Computer Software, Computer Software Documentation, and Technical Data for Commercial Items are licensed to the U.S. Government under vendor's standard commercial license.

Compaq shall not be liable for technical or editorial errors or omissions contained herein.

The information in this publication is subject to change without notice and is provided "AS IS" WITHOUT WARRANTY OF ANY KIND. THE ENTIRE RISK ARISING OUT OF THE USE OF THIS INFORMATION REMAINS WITH RECIPIENT. IN NO EVENT SHALL COMPAQ BE LIABLE FOR ANY DIRECT, CONSEQUENTIAL, INCIDENTAL, SPECIAL, PUNITIVE, OR OTHER DAMAGES WHATSOEVER (INCLUDING WITHOUT LIMITATION, DAMAGES FOR LOSS OF BUSINESS PROFITS, BUSINESS INTERRUPTION, OR LOSS OF BUSINESS INFORMATION), EVEN IF COMPAQ HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. THE FOREGOING SHALL APPLY REGARDLESS OF THE NEGLIGENCE OR OTHER FAULT OF EITHER PARTY AND REGARDLESS OF WHETHER SUCH LIABILITY SOUNDS IN CONTRACT, NEGLIGENCE, TORT, OR ANY OTHER THEORY OF LEGAL LIABILITY, AND NOTWITHSTANDING ANY FAILURE OF ESSENTIAL PURPOSE OF ANY LIMITED REMEDY.

The limited warranties for Compaq products are exclusively set forth in the documentation accompanying such products. Nothing herein should be construed as constituting a further or additional warranty.

ZK5433

The Compaq OpenVMS documentation set is available on CD-ROM.

Contents Index

Preface

Compaq BASIC for OpenVMS Alpha is the new name for DEC BASIC. Compaq BASIC for OpenVMS VAX is the new name for VAX BASIC. Any references to the former names in product documentation or other components should be construed as references to the Compaq BASIC names. Any references to BASIC or to Compaq BASIC apply to both products unless otherwise specified. References to the shortened names Alpha BASIC and VAX BASIC mean Compaq BASIC for OpenVMS Alpha and Compaq BASIC for OpenVMS VAX, respectively.

This manual describes BASIC language elements and syntax.

Intended Audience

This manual is intended for experienced applications programmers who have a fundamental understanding of the BASIC language. Some familiarity with your operating system is also recommended. This is not a tutorial manual.

Document Structure

This manual contains the following chapters and appendixes:

Chapter 1 summarizes BASIC program elements and structure.
Chapter 2 describes the environment commands (VAX BASIC only).
Chapter 3 describes the compiler directives.
Chapter 4 describes the statements and functions.
Appendix A lists the ASCII codes.
Appendix B lists the BASIC keywords.
Appendix C discusses differences between Alpha BASIC and VAX BASIC.

Chapters 2, 3, and 4 provide reference material on each BASIC language element. The language elements are arranged in alphabetical order within these chapters; each language element begins on a separate page. The descriptions include the following sections:

Definition A description of what the statement or command does.

Format The required syntax for the language element.

Syntax Rules Any rules governing the use of parameters, separators, or other syntax items, effect of the statement or command on program execution, and any restrictions governing its use.

Remarks Further explanations or restrictions about the statement or command.

Example One or more examples of the statement in a partial program. Where appropriate, explanatory text and program output are included.

Platform Labels

A platform is a combination of operating system and central processing unit (CPU) that provides a distinct environment in which to use a product (in this case, a language). This manual contains information for the following language platforms:

OpenVMS Alpha
OpenVMS VAX

Information in this manual applies to both supported platforms, unless it is otherwise noted. Platform-specific information is noted in the manual as follows:

Alpha BASIC refers to information that is correct for Compaq BASIC for OpenVMS Alpha systems.
VAX BASIC refers to information that is correct for Compaq BASIC for OpenVMS VAX systems.

Reader's Comments

Compaq welcomes your comments on this manual. Please send comments to either of the following addresses:

Internet basic_docs@compaq.com

Mail Compaq Computer Corporation
OSSG Documentation Group, ZKO3-4/U08
110 Spit Brook Rd.
Nashua, NH 03062-2698

How to Order Additional Documentation

If you have access to the World Wide Web, please visit our website at

http://www.openvms.digital.com/commercial/basic/basic_index.html

Click Software Product Description, and read the ordering information. Note the order numbers of the documents you want. For pricing and further information, call 1--800--282-6672.

Use the following World Wide Web address for information about how to order OpenVMS operating system documentation:

http://www.compaq.com/

If you need help deciding which documentation best meets your needs, call 1--800--282--6672.

Conventions

In this manual, every use of the name Compaq BASIC or the name BASIC applies to both Compaq BASIC for OpenVMS Alpha and Compaq BASIC for OpenVMS VAX software.

Table 1 shows the conventions used in this manual.

Table 1 Conventions Used in This Manual
Convention Description

$ A dollar sign ($) represents the OpenVMS DCL system prompt.

[Return] In examples, a key name enclosed in a box indicates that you press that key on the keyboard. (In text, a key name is not enclosed in a box.)
In the HTML version of this document, this convention appears as brackets, rather than a box.

Ctrl/ x The key combination Ctrl/ x indicates that you must hold down the key labeled Ctrl while you press another key, for example Ctrl/Y or Ctrl/Z.

KP n The phrase KP n indicates that you must press the key labeled with the number or character n on the numeric keypad, for example, KP3 or KP-.

PF1 x A sequence such as PF1 x indicates that you must first press and release the key labeled PF1, then press and release another key.

n A lowercase italic n indicates the generic use of a number.

... A horizontal ellipsis in examples indicates one of the following possibilities:

Additional optional arguments in a statement have been omitted.
The preceding item or items can be repeated one or more times.
Additional parameters, values, or other information can be entered.

.
.
. A vertical ellipsis indicates the omission of items from a code example or command format; the items are omitted because they are not important to the topic being discussed.

() In format descriptions, parentheses indicate that you must enclose the options in parentheses if you choose more than one.

[] In format descriptions, brackets indicate optional elements; you can select none, one, or all of the elements.

{ } In format descriptions, braces indicate that one element in a list is required. You must choose one and only one from the list.

boldface text Boldface text is used for the introduction of a new term.

italic text Italic text represents parameters, arguments, and information that can vary in system messages (for example, Internal error number), as well as book titles and emphasized information.

UPPERCASE Uppercase indicates the name of a command, routine, file, or file protection code, or the abbreviation for a system privilege.

**Table 1 Conventions Used in This Manual**
Convention	Description
$	A dollar sign ($) represents the OpenVMS DCL system prompt.
`[Return]`	In examples, a key name enclosed in a box indicates that you press that key on the keyboard. (In text, a key name is not enclosed in a box.) In the HTML version of this document, this convention appears as brackets, rather than a box.
Ctrl/ x	The key combination Ctrl/ x indicates that you must hold down the key labeled Ctrl while you press another key, for example Ctrl/Y or Ctrl/Z.
KP n	The phrase KP n indicates that you must press the key labeled with the number or character n on the numeric keypad, for example, KP3 or KP-.
PF1 x	A sequence such as PF1 x indicates that you must first press and release the key labeled PF1, then press and release another key.
n	A lowercase italic n indicates the generic use of a number.
...	A horizontal ellipsis in examples indicates one of the following possibilities: Additional optional arguments in a statement have been omitted. The preceding item or items can be repeated one or more times. Additional parameters, values, or other information can be entered.
. . .	A vertical ellipsis indicates the omission of items from a code example or command format; the items are omitted because they are not important to the topic being discussed.
()	In format descriptions, parentheses indicate that you must enclose the options in parentheses if you choose more than one.
[]	In format descriptions, brackets indicate optional elements; you can select none, one, or all of the elements.
{ }	In format descriptions, braces indicate that one element in a list is required. You must choose one and only one from the list.
boldface text	Boldface text is used for the introduction of a new term.
italic text	Italic text represents parameters, arguments, and information that can vary in system messages (for example, Internal error number), as well as book titles and emphasized information.
UPPERCASE	Uppercase indicates the name of a command, routine, file, or file protection code, or the abbreviation for a system privilege.

Table 2 defines mnemonics and other terms used in the syntax diagrams.

Table 2 Mnemonics and Other Terms Used in Syntax
Term Meaning

angle Angle in radians or degrees

array Array; syntax rules specify whether the bounds or dimensions can be specified

chnl I/O channel associated with a file

chnl-exp Numeric expression that specifies a channel number

com Specific to a COMMON block

cond Conditional expression; indicates that an expression can be either logical or relational

cond-exp Conditional expression

const Constant value

data-type Data type keyword

decimal-var Decimal variable

decl-item Array, record, or variable

def Specific to a DEF function

delim Delimiter

equiv-name File specification, device, or logical name to be assigned a logical name

err-num Run-time error number

exp Expression

ext-routine External function

external-param External parameter

file-spec File specification

func Specific to a FUNCTION subprogram

int Integer value

int-const Integer constant

int-exp Expression that represents an integer value

int-var Variable that contains an integer value

label Alphanumeric statement label

lex Lexical; used to indicate a component of a compiler directive

lex-exp Lexical expression

lex-var Lexical variable

line Statement line; may or may not be numbered

line-num Statement line number

lit Literal value, in quotation marks

log-exp Logical expression

log-name 1- to 63-character logical name to be associated with equiv-name

macro-id User identifier following the rules for BASIC identifiers

map Specific to a MAP statement

matrix Two-dimensional array

name Name or identifier; indicates the declaration of a name or the name of a BASIC structure, such as a SUB subprogram

num Numeric value

num-lit Numeric literal

param-list Parameter list, such as for a SUB subprogram

pass-mech Valid BASIC passing mechanism

prog-name Program name

real Floating-point value

real-exp Real expression

real-var Real variable

rel-exp Relational expression

relationship-type Oracle CDD/Repository protocol

replacement-token Identifier, keyword, compiler directive, literal constant, or operator

routine SUB subprogram or other callable procedure

str Character string

str-exp Expression that represents a character string

str-lit String literal

str-var Variable that contains a character string

sub Specific to a SUB subprogram

target Target point of a branch statement; either a line number or a label

unq-str Unique string

unsubs-var Unsubscripted variable, as opposed to an array element

var Variable

**Table 2 Mnemonics and Other Terms Used in Syntax**
Term	Meaning
angle	Angle in radians or degrees
array	Array; syntax rules specify whether the bounds or dimensions can be specified
chnl	I/O channel associated with a file
chnl-exp	Numeric expression that specifies a channel number
com	Specific to a COMMON block
cond	Conditional expression; indicates that an expression can be either logical or relational
cond-exp	Conditional expression
const	Constant value
data-type	Data type keyword
decimal-var	Decimal variable
decl-item	Array, record, or variable
def	Specific to a DEF function
delim	Delimiter
equiv-name	File specification, device, or logical name to be assigned a logical name
err-num	Run-time error number
exp	Expression
ext-routine	External function
external-param	External parameter
file-spec	File specification
func	Specific to a FUNCTION subprogram
int	Integer value
int-const	Integer constant
int-exp	Expression that represents an integer value
int-var	Variable that contains an integer value
label	Alphanumeric statement label
lex	Lexical; used to indicate a component of a compiler directive
lex-exp	Lexical expression
lex-var	Lexical variable
line	Statement line; may or may not be numbered
line-num	Statement line number
lit	Literal value, in quotation marks
log-exp	Logical expression
log-name	1- to 63-character logical name to be associated with equiv-name
macro-id	User identifier following the rules for BASIC identifiers
map	Specific to a MAP statement
matrix	Two-dimensional array
name	Name or identifier; indicates the declaration of a name or the name of a BASIC structure, such as a SUB subprogram
num	Numeric value
num-lit	Numeric literal
param-list	Parameter list, such as for a SUB subprogram
pass-mech	Valid BASIC passing mechanism
prog-name	Program name
real	Floating-point value
real-exp	Real expression
real-var	Real variable
rel-exp	Relational expression
relationship-type	Oracle CDD/Repository protocol
replacement-token	Identifier, keyword, compiler directive, literal constant, or operator
routine	SUB subprogram or other callable procedure
str	Character string
str-exp	Expression that represents a character string
str-lit	String literal
str-var	Variable that contains a character string
sub	Specific to a SUB subprogram
target	Target point of a branch statement; either a line number or a label
unq-str	Unique string
unsubs-var	Unsubscripted variable, as opposed to an array element
var	Variable

Contents

Index

Definition	A description of what the statement or command does.
Format	The required syntax for the language element.
Syntax Rules	Any rules governing the use of parameters, separators, or other syntax items, effect of the statement or command on program execution, and any restrictions governing its use.
Remarks	Further explanations or restrictions about the statement or command.
Example	One or more examples of the statement in a partial program. Where appropriate, explanatory text and program output are included.

Internet	basic_docs@compaq.com
Mail	Compaq Computer Corporation OSSG Documentation Group, ZKO3-4/U08 110 Spit Brook Rd. Nashua, NH 03062-2698