Constants can be used throughout Natural programs. This document discusses the types of constants that are supported and how they are used.
This document covers the following topics:
The following topics are covered below:
A numeric constant may contain 1 to 29 numeric digits, a special character as decimal separator (period or comma) and a sign.
Examples:
1234 +1234 -1234 12.34 +12.34 -12.34
MOVE 3 TO #XYZ COMPUTE #PRICE = 23.34 COMPUTE #XYZ = -103 COMPUTE #A = #B * 6074
Numeric constants are represented internally in packed form (format P); exception: if a numeric constant is used in an arithmetic operation in which the other operand is an integer variable (format I), the numeric constant is represented in integer form (format I).
When numeric constants are used within one of the statements
COMPUTE,
MOVE, or
DEFINE DATA with
INIT option,
Natural checks at compilation time whether a constant value fits into the
corresponding field. This avoids runtime errors in situations where such an
error condition can already be detected during compilation.
The following topics are covered below:
An alphanumeric constant may contain 1 to 1 1073741824 bytes (1 GB) of alphanumeric characters.
An alphanumeric constant must be enclosed in either apostrophes (')
'text'
or quotation marks (")
"text"
Examples:
MOVE 'ABC' TO #FIELDX MOVE '% INCREASE' TO #TITLE DISPLAY "LAST-NAME" NAME
Note:
An alphanumeric constant that is used to assign a value to a
user-defined variable must not be
split between statement lines.
If you want an apostrophe to be part of an alphanumeric constant that is enclosed in apostrophes, you must write this as two apostrophes or as a single quotation mark.
If you want an apostrophe to be part of an alphanumeric constant that is enclosed in quotation marks, you write this as a single apostrophe.
Example:
If you want the following to be output:
HE SAID, 'HELLO'
you can use any of the following notations:
WRITE 'HE SAID, ''HELLO''' WRITE 'HE SAID, "HELLO"' WRITE "HE SAID, ""HELLO""" WRITE "HE SAID, 'HELLO'"
Note:
If quotation marks are not converted to apostrophes as shown
above, this is due to the setting of keyword subparameter
TQMARK of profile parameter
CMPO or macro
NTCMPO (Translate
Quotation Marks); ask your Natural administrator for details.
Alphanumeric constants may be concatenated to form a single value by use of a hyphen.
Examples:
MOVE 'XXXXXX' - 'YYYYYY' TO #FIELD MOVE "ABC" - 'DEF' TO #FIELD
In this way, alphanumeric constants can also be concatenated with hexadecimal constants.
The following topics are covered below:
A Unicode text constant must be preceded by the character
U and enclosed in either apostrophes (')
U'text'
or quotation marks (")
U"text"
Example:
U'HELLO'
The compiler stores this text constant in the generated program in Unicode format (UTF-16).
If you want an apostrophe to be part of a Unicode text constant that is enclosed in apostrophes, you must write this as two apostrophes or as a single quotation mark.
If you want an apostrophe to be part of a Unicode text constant that is enclosed in quotation marks, you write this as a single apostrophe.
Example:
If you want the following to be output:
HE SAID, 'HELLO'
you can use any of the following notations:
WRITE U'HE SAID, ''HELLO''' WRITE U'HE SAID, "HELLO"' WRITE U"HE SAID, ""HELLO""" WRITE U"HE SAID, 'HELLO'"
Note:
If quotation marks are not converted to apostrophes as shown
above, this is due to the setting of the profile parameter
TQ (Translate
Quotation Marks); ask your Natural administrator for details.
The following syntax is used to supply a Unicode character or a Unicode string by its hexadecimal notation:
UH'hhhh...'
where h represents a
hexadecimal digit (0-9, A-F). Since a UTF-16 Unicode character consists of a
double-byte, the number of hexadecimal characters supplied has to be a multiple
of four.
Example:
This example defines the string 45.
UH'00340035'
Concatenation of Unicode text constants (U) and Unicode hexadecimal constants (UH) is allowed.
Valid Example:
MOVE U'XXXXXX' - UH'00340035' TO #FIELD
Unicode text constants or Unicode hexadecimal constants cannot be concatenated with code page alphanumeric constants or H constants.
Invalid Example:
MOVE U'ABC' - 'DEF' TO #FIELD MOVE UH'00340035' - H'414243' TO #FIELD
Further Valid Example:
DEFINE DATA LOCAL 1 #U10 (U10) /* Unicode variable with 10 (UTF-16) characters, total byte length = 20 1 #UD (U) DYNAMIC /* Unicode variable with dynamic length END-DEFINE * #U10 := U'ABC' /* Constant is created as X'004100420043' in the object, the UTF-16 representation for string 'ABC'. #U10 := UH'004100420043' /* Constant supplied in hexadecimal format only, corresponds to U'ABC' #U10 := U'A'-UH'0042'-U'C' /* Constant supplied in mixed formats, corresponds to U'ABC'. END
The following topics are covered below:
A date constant may be used in conjunction with a format D variable.
Date constants may have the following formats:
D'yyyy-mm-dd'
|
International date format |
D'dd.mm.yyyy'
|
German date format |
D'dd/mm/yyyy'
|
European date format |
D'mm/dd/yyyy'
|
US date format |
where dd represents the
number of the day, mm the number of the
month and yyyy the year.
Example:
DEFINE DATA LOCAL 1 #DATE (D) END-DEFINE ... MOVE D'2004-03-08' TO #DATE ...
The default date format is controlled by the profile parameter
DTFORM
(Date Format) as set by the Natural administrator.
A time constant may be used in conjunction with a format T variable.
A time constant has the following format:
T'hh:ii:ss'
where hh represents hours,
ii minutes and
ss seconds.
Example:
DEFINE DATA LOCAL 1 #TIME (T) END-DEFINE ... MOVE T'11:33:00' TO #TIME ...
A time variable (format T) can contain date and time information,
date information being a subset of time information; however, with a
"normal" time constant (prefix T) only the time
information of a time variable can be handled:
T'hh:ii:ss'
With an extended time constant (prefix E), it is
possible to handle the full content of a time variable, including the date
information:
E'yyyy-mm-dd hh:ii:ss'
Apart from that, the use of an extended time constant in conjunction with a time variable is the same as for a normal time constant.
Note:
The format in which the date information has to be specified
in an extended time constant depends on the setting of the profile parameter
DTFORM.
The extended time constant shown above assumes DTFORM=I
(international date format).
The following topics are covered below:
A hexadecimal constant may be used to enter a value which cannot be entered as a standard keyboard character.
A hexadecimal constant may contain 1 to 1073741824 bytes (1 GB) of alphanumeric characters.
A hexadecimal constant is prefixed with an H. The
constant itself must be enclosed in apostrophes and may consist of the
hexadecimal characters 0 - 9, A - F. Two hexadecimal characters are required to
represent one byte of data.
The hexadecimal representation of a character varies, depending on whether your computer uses an ASCII or EBCDIC character set. When you transfer hexadecimal constants to another computer, you may therefore have to convert the characters.
ASCII examples:
H'313233' (equivalent to the alphanumeric constant '123') H'414243' (equivalent to the alphanumeric constant 'ABC')
EBCDIC examples:
H'F1F2F3' (equivalent to the alphanumeric constant '123') H'C1C2C3' (equivalent to the alphanumeric constant 'ABC')
When a hexadecimal constant is transferred to another field, it will be treated as an alphanumeric value (format A).
The data transfer of an alphanumeric value (format A) to a field
which is defined with a format other than A,U or B is not allowed. Therefore, a
hexadecimal constant used as initial value in a
DEFINE DATA
statement is rejected with the syntax error NAT0094 if the corresponding
variable is not of format A, U or B.
Example:
DEFINE DATA LOCAL 1 #I(I2) INIT <H'000F'> /* causes a NAT0094 syntax error END-DEFINE
Hexadecimal constants may be concatenated by using a hyphen between the constants.
ASCII example:
H'414243' - H'444546' (equivalent to 'ABCDEF')
EBCDIC example:
H'C1C2C3' - H'C4C5C6' (equivalent to 'ABCDEF')
In this way, hexadecimal constants can also be concatenated with alphanumeric constants.
The logical constants TRUE and FALSE may
be used to assign a logical value to a field defined with Format L.
Example:
DEFINE DATA LOCAL 1 #FLAG (L) END-DEFINE ... MOVE TRUE TO #FLAG ... IF #FLAG ... statement ... MOVE FALSE TO #FLAG END-IF ...
Floating point constants can be used with variables defined with format F.
Example:
DEFINE DATA LOCAL 1 #FLT1 (F4) END-DEFINE ... COMPUTE #FLT1 = -5.34E+2 ...
Attribute constants can be used with variables defined with format C (control variables). This type of constant must be enclosed within parentheses.
The following attributes may be used:
| Attribute | Description |
|---|---|
AD=D
|
default |
AD=B
|
blinking |
AD=I
|
intensified |
AD=N
|
non-display |
AD=V
|
reverse video |
AD=U
|
underlined |
AD=C
|
cursive/italic |
AD=Y
|
dynamic attribute |
AD=P
|
protected |
CD=BL
|
blue |
CD=GR |
green |
CD=NE
|
neutral |
CD=PI
|
pink |
CD=RE
|
red |
CD=TU
|
turquoise |
CD=YE
|
yellow |
See also session parameters AD and
CD.
Example:
DEFINE DATA LOCAL 1 #ATTR (C) 1 #FIELD (A10) END-DEFINE ... MOVE (AD=I CD=BL) TO #ATTR ... INPUT #FIELD (CV=#ATTR) ...
The handle constant NULL-HANDLE can be used with
object handles.
If you need to use the same constant value several times in a program, you can reduce the maintenance effort by defining a named constant:
Define a field in the DEFINE DATA statement,
assign a constant value to it, and
use the field name in the program instead of the constant value.
Thus, when the value has to be changed, you only have to change it
once in the DEFINE DATA statement and not everywhere in the
program where it occurs.
You specify the constant value in angle brackets with the
keyword CONSTANT after the
field definition in the DEFINE DATA statement.
If the value is alphanumeric, it must be enclosed in apostrophes.
If the value is text in Unicode format, it must be preceded by
the character U and must be enclosed in apostrophes.
If the value is in hexadecimal Unicode format, it must be
preceded by the characters UH and must be enclosed in apostrophes.
Example:
DEFINE DATA LOCAL 1 #FIELDA (N3) CONSTANT <100> 1 #FIELDB (A5) CONSTANT <'ABCDE'> 1 #FIELDC (U5) CONSTANT <U'ABCDE'> 1 #FIELDD (U5) CONSTANT <UH'00410042004300440045'> END-DEFINE ...
During the execution of the program, the value of such a named constant cannot be modified.