This document describes purpose and use of logical condition
criteria that can be used in the statements FIND
,
READ
,
HISTOGRAM
,
ACCEPT
/REJECT
,
IF
,
DECIDE FOR
and
REPEAT
.
The following topics are covered:
BREAK Option - Compare Current Value with Value of Previous Loop Pass
IS Option - Check whether Content of Alphanumeric or Unicode Field can be Converted
MASK Option - Check Selected Positions of a Field for Specific Content
MODIFIED Option - Check whether Field Content has been Modified
SPECIFIED Option - Check whether a Value is Passed for an Optional Parameter
The basic criterion is a relational expression. Multiple relational
expressions may be combined with logical operators (AND
,
OR
) to form complex criteria.
Arithmetic expressions may also be used to form a relational expression.
Logical condition criteria can be used in the following statements:
Statement | Usage |
---|---|
FIND
|
A WHERE clause containing logical condition
criteria may be used to indicate criteria in addition to the basic selection
criteria as specified in the WITH clause. The logical condition
criteria specified with the WHERE clause are evaluated after the
record has been selected and read.
In a |
READ
|
A WHERE clause containing logical condition
criteria may be used to specify whether a record that has just been read is to
be processed. The logical condition criteria are evaluated after the record has
been read.
|
HISTOGRAM
|
A WHERE clause containing logical condition
criteria may be used to specify whether the value that has just been read is to
be processed. The logical condition criteria are evaluated after the value has
been read.
|
ACCEPT /REJECT
|
An IF clause may be used with an
ACCEPT or REJECT statement to specify logical
condition criteria in addition to that specified when the record was
selected/read with a FIND , READ , or
HISTOGRAM statement. The logical condition criteria are evaluated
after the record has been read and after record processing has started.
|
IF
|
Logical condition criteria are used to control statement execution. |
DECIDE
FOR
|
Logical condition criteria are used to control statement execution. |
REPEAT
|
The UNTIL or WHILE clause of a
REPEAT statement contain logical condition criteria which
determine when a processing loop is to be terminated.
|
Syntax:
operand1 |
|
operand2 |
Operand Definition Table:
Operand | Possible Structure | Possible Formats | Referencing Permitted | Dynamic Definition | |||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
operand1
|
C | S | A | N | E | A | U | N | P | I | F | B | D | T | L | G | O | yes | yes | ||
operand2
|
C | S | A | N | E | A | U | N | P | I | F | B | D | T | L | G | O | yes | no |
For an explanation of the Operand Definition Table shown above, see Syntax Symbols and Operand Definition Tables in the Statements documentation.
In the "Possible Structure" column of the table above,
"E" stands for arithmetic expressions; that is, any arithmetic
expression may be specified as an operand within the relational expression. For
further information on arithmetic expressions, see
arithmetic-expression
in the COMPUTE
statement description.
Explanation of the comparison operators:
Comparison Operator | Explanation |
---|---|
|
equal to |
|
not equal to |
|
less than |
|
greater than or equal to |
|
not less than |
|
greater than |
|
less than or equal to |
|
not greater than |
IF NAME = 'SMITH' IF LEAVE-DUE GT 40 IF NAME = #NAME
For information on comparing arrays in a relational expression, see Processing of Arrays.
Note:
If a floating-point operand is used, comparison is performed in
floating point. Floating-point
numbers as such have only a limited precision; therefore,
rounding/truncation errors cannot be precluded when numbers are converted
to/from floating-point representation.
The following example shows how arithmetic expressions can be used in logical conditions:
IF #A + 3 GT #B - 5 AND #C * 3 LE #A + #B
If the operands in a relation expression are handles, only
EQUAL
and NOT EQUAL
operators may be used.
Syntax:
|
|
operand2 |
Operand Definition Table:
Operand | Possible Structure | Possible Formats | Referencing Permitted | Dynamic Definition | |||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
operand1
|
C | S | A | N | A | U | B | yes | yes | ||||||||||||
operand2
|
C | S | A | N | A | U | B | yes | no | ||||||||||||
operand3 |
C | S | N | P | I | B | yes | no | |||||||||||||
operand4 |
C | S | N | P | I | yes | no | ||||||||||||||
operand5 |
C | S | N | P | I | yes | no | ||||||||||||||
operand6 |
C | S | N | P | I | yes | no |
With the SUBSTRING
option, you can compare a
part of an alphanumeric, a binary or a Unicode field. After the field
name (operand1
) you specify first the
starting position (operand3
) and then
the length
(operand4
) of the field portion to be
compared.
Also, you can compare a field value with part of another field
value. After the field name (operand2
)
you specify first the starting position
(operand5
) and then the length
(operand6
) of the field portion
operand1
is to be compared with.
You can also combine both forms, that is, you can specify a
SUBSTRING
for both
operand1
and
operand2
.
The following expression compares the 5th to 12th position inclusive
of the value in field #A
with the value of field
#B
:
SUBSTRING(#A,5,8) = #B
- where 5 is the starting position and 8 is the length.
The following expression compares the value of field #A
with the 3rd to 6th position inclusive of the value in field
#B
:
#A = SUBSTRING(#B,3,4)
Note:
If you omit
operand3/operand5
,
the starting position is assumed to be 1. If you omit
operand4/operand6
,
the length is assumed to be from the starting position to the end of the
field.
Syntax:
operand1 |
|
operand2 | ||||||||
OR
|
|
operand3 | ||||||||
THRU operand4 [BUT NOT operand5 [THRU operand6]]
|
Operand Definition Table:
Operand | Possible Structure | Possible Formats | Referencing Permitted | Dynamic Definition | |||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
operand1
|
C | S | A | N* | E | A | U | N | P | I | F | B | D | T | G | O | yes | no | |||
operand2
|
C | S | A | N* | E | A | U | N | P | I | F | B | D | T | G | O | yes | no | |||
operand3 |
C | S | A | N* | E | A | U | N | P | I | F | B | D | T | G | O | yes | no | |||
operand4 |
C | S | A | N* | E | A | U | N | P | I | F | B | D | T | G | O | yes | no | |||
operand5 |
C | S | A | N* | E | A | U | N | P | I | F | B | D | T | G | O | yes | no | |||
operand6 |
C | S | A | N* | E | A | U | N | P | I | F | B | D | T | G | O | yes | no |
* Mathematical functions and system variables are permitted. Break functions are not permitted.
operand3
can also be
specified using a MASK
or SCAN
option; that is, it
can be specified as:
MASK
(mask-definition)
[operand]
|
MASK
operand
|
SCAN
operand |
For details on these options, see the sections MASK Option and SCAN Option.
IF #A = 2 OR = 4 OR = 7 IF #A = 5 THRU 11 BUT NOT 7 THRU 8
Syntax:
operand1 |
This option is used in conjunction with a logical variable (format
L). A logical variable may take the value TRUE
or
FALSE
. As operand1
you
specify the name of the logical variable to be used.
Operand Definition Table:
Operand | Possible Structure | Possible Formats | Referencing Permitted | Dynamic Definition | |||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
operand1
|
C | S | A | L | no | no |
** Example 'LOGICX05': Logical variable in logical condition ************************************************************************ DEFINE DATA LOCAL 1 #SWITCH (L) INIT <true> 1 #INDEX (I1) END-DEFINE * FOR #INDEX 1 5 WRITE NOTITLE #SWITCH (EM=FALSE/TRUE) 5X 'INDEX =' #INDEX WRITE NOTITLE #SWITCH (EM=OFF/ON) 7X 'INDEX =' #INDEX IF #SWITCH MOVE FALSE TO #SWITCH ELSE MOVE TRUE TO #SWITCH END-IF /* SKIP 1 END-FOR END
Output of Program LOGICX05
:
TRUE INDEX = 1 ON INDEX = 1 FALSE INDEX = 2 OFF INDEX = 2 TRUE INDEX = 3 ON INDEX = 3 FALSE INDEX = 4 OFF INDEX = 4 TRUE INDEX = 5 ON INDEX = 5
Database fields and user-defined variables may be used to construct logical condition criteria. A database field which is a multiple-value field or is contained in a periodic group can also be used. If a range of values for a multiple-value field or a range of occurrences for a periodic group is specified, the condition is true if the search value is found in any value/occurrence within the specified range.
Each value used must be compatible with the field used on the opposite side of the expression. Decimal notation may be specified only for values used with numeric fields, and the number of decimal positions of the value must agree with the number of decimal positions defined for the field.
If the operands are not of the same format, the second operand is converted to the format of the first operand.
The following table shows which operand formats can be used together in a logical condition:
operand1 | operand2 | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
A | U | Bn (n=<4) | Bn (n>=5) | D | T | I | F | L | N | P | GH | OH | |
A | Y | Y | Y | Y | |||||||||
U | Y | Y | [2] | [2] | |||||||||
Bn (n=<4) | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | |||
Bn (n>=5) | Y | Y | Y | Y | |||||||||
D | Y | Y | Y | Y | Y | Y | Y | ||||||
T | Y | Y | Y | Y | Y | Y | Y | ||||||
I | Y | Y | Y | Y | Y | Y | Y | ||||||
F | Y | Y | Y | Y | Y | Y | Y | ||||||
L | |||||||||||||
N | Y | Y | Y | Y | Y | Y | Y | ||||||
P | Y | Y | Y | Y | Y | Y | Y | ||||||
GH [1] | Y | ||||||||||||
OH [1] | Y |
Notes:
If two values are compared as alphanumeric values, the shorter value is assumed to be extended with trailing blanks in order to get the same length as the longer value.
If two values are compared as binary values, the shorter value is assumed to be extended with leading binary zeroes in order to get the same length as the longer value.
If two values are compared as Unicode values, trailing blanks are removed from both values before the ICU collation algorithm is used to compare the two resulting values. See also Logical Condition Criteria in the Unicode and Code Page Support documentation.
A1(A1) := 'A' A5(A5) := 'A ' B1(B1) := H'FF' B5(B5) := H'00000000FF' U1(U1) := UH'00E4' U2(U2) := UH'00610308' IF A1 = A5 THEN ... /* TRUE IF B1 = B5 THEN ... /* TRUE IF U1 = U2 THEN ... /* TRUE
If an array is compared with a scalar value, each element of the
array will be compared with the scalar value. The condition will be true if at
least one of the array elements meets the condition (OR
operation).
If an array is compared with an array, each element in the array is
compared with the corresponding element of the other array. The result is true
only if all element comparisons meet the condition (AND
operation).
See also Processing of Arrays.
Note:
An Adabas phonetic descriptor cannot be used within a logical
condition.
FIND EMPLOYEES-VIEW WITH CITY = 'BOSTON' WHERE SEX = 'M' READ EMPLOYEES-VIEW BY NAME WHERE SEX = 'M' ACCEPT IF LEAVE-DUE GT 45 IF #A GT #B THEN COMPUTE #C = #A + #B REPEAT UNTIL #X = 500
Logical condition criteria may be combined using the Boolean
operators AND
, OR
and NOT
. Parentheses
may also be used to indicate logical grouping.
The operators are evaluated in the following order:
Priority | Operator | Meaning |
---|---|---|
1 | ( )
|
Parentheses |
2 | NOT
|
Negation |
3 | AND
|
AND operation
|
4 | OR
|
OR operation
|
The following
logical-condition-criteria
may be
combined by logical operators to form a complex
logical-expression:
The syntax for a
logical-expression
is as follows:
[NOT]
|
logical-condition-criterion |
OR
|
logical-expression | |||||||
AND
|
FIND STAFF-VIEW WITH CITY = 'TOKYO' WHERE BIRTH GT 19610101 AND SEX = 'F' IF NOT (#CITY = 'A' THRU 'E')
For information on comparing arrays in a logical expression, see Processing of Arrays.
Note:
If multiple logical-condition-criteria are connected with AND
, the
evaluation terminates as soon as the first of these criteria is not true. If multiple
logical-condition-criteria are connected with OR
, the evaluation terminates
as soon as the first of these criteria is true.
The BREAK
option allows the current value or a portion
of a value of a field to be compared with the value contained in the same field
in the previous pass through the processing loop.
Syntax:
BREAK [OF]
operand1
[/n/]
|
Operand Definition Table:
Operand | Possible Structure | Possible Formats | Referencing Permitted | Dynamic Definition | |||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
operand1
|
S | A | U | N | P | I | F | B | D | T | L | yes | no |
Syntax Element Description:
** Example 'LOGICX03': BREAK option in logical condition ************************************************************************ DEFINE DATA LOCAL 1 EMPLOY-VIEW VIEW OF EMPLOYEES 2 NAME 2 FIRST-NAME 2 BIRTH * 1 #BIRTH (A8) END-DEFINE * LIMIT 10 READ EMPLOY-VIEW BY BIRTH MOVE EDITED BIRTH (EM=YYYYMMDD) TO #BIRTH /* IF BREAK OF #BIRTH /6/ NEWPAGE IF LESS THAN 5 LINES LEFT WRITE / '-' (50) / END-IF /* DISPLAY NOTITLE BIRTH (EM=YYYY-MM-DD) NAME FIRST-NAME END-READ END
Output of Program LOGICX03
:
DATE NAME FIRST-NAME OF BIRTH ---------- -------------------- -------------------- 1940-01-01 GARRET WILLIAM 1940-01-09 TAILOR ROBERT 1940-01-09 PIETSCH VENUS 1940-01-31 LYTTLETON BETTY -------------------------------------------------- 1940-02-02 WINTRICH MARIA 1940-02-13 KUNEY MARY 1940-02-14 KOLENCE MARSHA 1940-02-24 DILWORTH TOM -------------------------------------------------- 1940-03-03 DEKKER SYLVIA 1940-03-06 STEFFERUD BILL
Syntax:
operand1 IS (format) |
This option is used to check whether the content of an alphanumeric
or Unicode field (operand1
) can be
converted to a specific other format.
Operand Definition Table:
Operand | Possible Structure | Possible Formats | Referencing Permitted | Dynamic Definition | |||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
operand1
|
C | S | A | N | A | U | yes | no |
The format
for which the
check is performed can be:
Nll.ll | Numeric with length ll.ll. |
Fll | Floating point with length ll. |
D | Date. The following date formats are possible:
dd-mm-yy, dd-mm-yyyy,
ddmmyyyy (dd = day,
mm = month, yy or
yyyy = year). The sequence of the day, month and
year components as well as the characters between the components are determined
by the profile parameter DTFORM (which is
described in the Parameter Reference).
|
T | Time (according to the default time display format). |
Pll.ll | Packed numeric with length ll.ll. |
Ill | Integer with length ll. |
When the check is performed, leading and trailing blanks in
operand1
will be ignored.
The IS
option may, for example, be used to check the
content of a field before the mathematical function
VAL
(extract numeric value from an alphanumeric field) is used to ensure that it
will not result in a runtime error.
Note:
The IS
option cannot be used to check if the value
of an alphanumeric field is in the specified "format", but if it
can be converted to that "format". To check if a value is
in a specific format, you can use the MASK
option. For further
information, see MASK Option
Compared with IS Option and
Checking Packed or Unpacked Numeric
Data.
** Example 'LOGICX04': IS option as format/length check ************************************************************************ DEFINE DATA LOCAL 1 #FIELDA (A10) /* INPUT FIELD TO BE CHECKED 1 #FIELDB (N5) /* RECEIVING FIELD OF VAL FUNCTION 1 #DATE (A10) /* INPUT FIELD FOR DATE END-DEFINE * INPUT #DATE #FIELDA IF #DATE IS(D) IF #FIELDA IS (N5) COMPUTE #FIELDB = VAL(#FIELDA) WRITE NOTITLE 'VAL FUNCTION OK' // '=' #FIELDA '=' #FIELDB ELSE REINPUT 'FIELD DOES NOT FIT INTO N5 FORMAT' MARK *#FIELDA END-IF ELSE REINPUT 'INPUT IS NOT IN DATE FORMAT (YY-MM-DD) ' MARK *#DATE END-IF * END
Output of Program LOGICX04
:
#DATE 150487 #FIELDA INPUT IS NOT IN DATE FORMAT (YY-MM-DD)
With the MASK
option, you can check selected
positions of a field for specific content.
The following topics are covered below:
Syntax:
operand1 |
|
MASK
(mask-definition)
[operand2]
|
Operand Definition Table:
Operand | Possible Structure | Possible Formats | Referencing Permitted | Dynamic Definition | |||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
operand1
|
C | S | A | N | A | U | N | P | yes | no | |||||||||||
operand2
|
C | S | A | U | N | P | B | yes | no |
operand2
can only be used
if the mask-definition
contains at
least one X
. operand1
and
operand2
must be format-compatible:
If operand1
is of
format A, operand2
must be of format A,
B, N or U.
If operand1
is of
format U, operand2
must be of format A,
B, N or U.
If operand1
is of
format N or P, operand2
must be of
format N or P.
An X
in the
mask-definition
selects the
corresponding positions of the content of
operand1
and
operand2
for comparison.
Apart from a constant
mask-definition
(see above), you may
also specify a variable mask definition.
Syntax:
operand1 |
|
MASK
operand2 |
Operand Definition Table:
Operand | Possible Structure | Possible Formats | Referencing Permitted | Dynamic Definition | |||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
operand1
|
C | S | A | N | A | U | N | P | yes | no | |||||||||||
operand2
|
S | A | U | yes | no |
The content of operand2
will be taken as the mask definition. Trailing blanks in
operand2
will be ignored.
If operand1
is of
format A, N or P, operand2
must be of
format A.
If operand1
is of
format U, operand2
must be of format U.
The following characters may be used within a mask definition (the
mask definition is contained in mask-definition
for a
constant mask and operand2
for a
variable mask):
Character | Meaning |
---|---|
. or ? or
_ |
A period, question mark or underscore indicates a single position that is not to be checked. |
* or % |
An asterisk or percent mark is used to indicate any number of positions not to be checked. |
/ |
A slash (/) is used to check if a value ends with a
specific character (or string of characters).
For example, the following condition will be true if
there is either an IF #FIELD = MASK (*'E'/) |
A
|
The position is to be checked for an alphabetical character (upper or lower case). |
'c' |
One or more positions are to be checked for the characters bounded by apostrophes. Alphanumeric characters with hexadecimal numbers lower than H'40' (blank) are not allowed. The characters to be checked for are dependent on the TQMARK parameter:
If |
C
|
The position is to be checked for an alphabetical character (upper or lower case), a numeric character, or a blank. |
DD
|
The two positions are to be checked for a valid day
notation (01 - 31; dependent on the values of MM and
YY/YYYY , if specified; see also
Checking
Dates).
|
H
|
The position is to be checked for hexadecimal content (A - F, 0 - 9). |
JJJ
|
The positions are to be checked for a valid Julian
Day; that is, the day number in the year (001-366, dependent on the value of
YY/YYYY , if specified. See also
Checking
Dates.)
|
L
|
The position is to be checked for a lower-case alphabetical character (a - z). |
MM
|
The positions are to be checked for a valid month (01 - 12); see also Checking Dates. |
N
|
The position is to be checked for a numeric digit. |
n... |
One (or more) positions are to be checked for a
numeric value in the range 0 -
n .
|
n1-n2 or
n1:n2
|
The positions are checked for a numeric value in the
range n1-n2.
n1 and n2 must be of the same length. |
P
|
The position is to be checked for a displayable character (U, L, N or S). |
S
|
The position is to be checked for special characters. |
U
|
The position is to be checked for an upper-case alphabetical character (A - Z). |
X
|
The position is to be checked against the equivalent
position in the value (operand2 )
following the mask-definition.
|
YY
|
The two positions are to be checked for a valid year (00 - 99). See also Checking Dates. |
YYYY
|
The four positions are checked for a valid year (0000
- 2699). Use the
COMPOPT option
MASKCME=ON to restrict the
range of valid years to 1582 - 2699; see also
Checking
Dates. If the profile parameter
MAXYEAR
is set to 9999, the upper year limit is 9999.
|
Z
|
The position is to be checked for a character whose
left half-byte is hexadecimal A - F, and whose right half-byte is hexadecimal 0 - 9.
This may be used to correctly check for numeric digits
in negative numbers. With Within a mask, use only one |
The definition of the character properties (for example, special
character) may be modified using the
SCTAB
profile parameter.
If the CP
profile parameter is set to
a value other than OFF
, the character properties (such as upper or
lower case alphabetical character) derive from the character properties of the
code page that is being used for the Natural session. As a consequence, for
example, the characters recognized as alphabetical characters may be different
from the default characters a - z and A - Z.
The length of the mask determines how many positions are to be checked.
DEFINE DATA LOCAL 1 #CODE (A15) END-DEFINE ... IF #CODE = MASK (NN'ABC'....NN) ...
In the above example, the first two positions of
#CODE
are to be checked for numeric content. The three following
positions are checked for the contents ABC
. The next four
positions are not to be checked. Positions ten and eleven are to be checked for
numeric content. Positions twelve to fifteen are not to be checked.
Only one date may be checked within a given mask. When the same
date component (JJJ
, DD
, MM
,
YY
or YYYY
) is specified more than once in the mask,
only the value of the last occurrence is checked for consistency with other
date components.
When dates are checked for a day (DD
) and no month
(MM
) is specified in the mask, the current month will be
assumed.
When dates are checked for a day (DD
) or a Julian day
(JJJ
) and no year (YY
or YYYY
) is
specified in the mask, the current year will be assumed.
When dates are checked for a 2-digit year (YY
), the
current century will be assumed if no Sliding or Fixed Window is set. For more
details about Sliding or Fixed Windows, refer to profile parameter
YSLW
in the
Parameter Reference.
MOVE 1131 TO #DATE (N4) IF #DATE = MASK (MMDD)
In this example, month and day are checked for validity. The value for month (11) will be considered valid, whereas the value for day (31) will be invalid since the 11th month has only 30 days.
IF #DATE(A8) = MASK (MM'/'DD'/'YY)
In this example, the content of the field #DATE
is be
checked for a valid date with the format MM/DD/YY
(month/day/year).
IF #DATE (A8) = MASK (1950-2020MMDD)
In this example, the content of field #DATE
is
checked for a four-digit number in the range 1950 to 2020 followed by a valid
month and day in the current year.
Note:
Although apparent, the above mask does not allow to check for
a valid date in the years 1950 through 2020, because the numeric value range
1950-2020 is checked independent of the validation of month and day. The check
will deliver the intended results except for February, 29, where the result
depends on whether the current year is a leap year or not. To check for a
specific year range in addition to the date validation, code one check for the
date validation and another for the range validation:
IF #DATE (A8) = MASK (YYYYMMDD) AND #DATE = MASK (1950-2020)
IF #DATE (A4) = MASK (19-20YY)
In this example, the content of field #DATE
is
checked for a two-digit number in the range 19 to 20 followed by a valid
two-digit year (00 through 99). The century is supplied by Natural as described
above.
Note:
Although apparent, the above mask does not allow to check for a
valid year in the range 1900 through 2099, because the numeric value range
19-20 is checked independent of the year validation. To check for year ranges,
code one check for the date validation and another for the range
validation:
IF #DATE (A10) = MASK (YYYY'-'MM'-'DD) AND #DATE = MASK (19-20)
If the value for the mask check is to be taken from either a
constant or a variable, this value
(operand2
) must be specified
immediately following the
mask-definition
.
operand2
must be at least
as long as the mask.
In the mask, you indicate each position to be checked with an
X
, and each position not to be checked with a period (.) or a
question mark (?) or an underscore (_).
DEFINE DATA LOCAL 1 #NAME (A15) END-DEFINE ... IF #NAME = MASK (..XX) 'ABCD' ...
In the above example, it is checked whether the field
#NAME
contains CD
in the third and fourth positions.
Positions one and two are not checked.
The length of the mask determines how many positions are to be checked. The mask is left-justified against any field or constant used in the mask operation. The format of the field (or constant) on the right side of the expression must be the same as the format of the field on the left side of the expression.
If the field to be checked
(operand1
) is of format A, any constant
used (operand2
) must be enclosed in
apostrophes. If the field is numeric, the value used must be a numeric constant
or the content of a numeric database field or user-defined variable.
In either case, any characters/digits within the value specified
whose positions do not match the X
indicator within the mask are
ignored.
The result of the MASK
operation is true when the
indicated positions in both values are identical.
** Example 'LOGICX01': MASK option in logical condition ************************************************************************ DEFINE DATA LOCAL 1 EMPLOY-VIEW VIEW OF EMPLOYEES 2 CITY END-DEFINE * HISTOGRAM EMPLOY-VIEW CITY IF CITY = MASK (....XX) '....NN' DISPLAY NOTITLE CITY *NUMBER END-IF END-HISTOGRAM * END
In the above example, the record will be accepted if the fifth and
sixth positions of the field CITY
each contain the character
N
.
When performing range checks, the number of positions verified in
the supplied variable is defined by the precision of the value supplied in the
mask specification. For example, a mask of (...193...)
will verify
positions 4 to 6 for a three-digit number in the range 000 to 193.
Additional Examples of Mask Definitions:
In this example, each character of #NAME
is
checked for an alphabetical character:
IF #NAME (A10) = MASK (AAAAAAAAAA)
In this example, positions 4 to 6 of #NUMBER
are
checked for a numeric value:
IF #NUMBER (A6) = MASK (...NNN)
In this example, positions 4 to 6 of #VALUE
are
to be checked for the value 123
:
IF #VALUE(A10) = MASK (...'123')
This example will check if #LICENSE
contains a
license number which begins with NY-
and whose last five
characters are identical to the last five positions of #VALUE
:
DEFINE DATA LOCAL 1 #VALUE(A8) 1 #LICENSE(A8) END-DEFINE INPUT 'ENTER KNOWN POSITIONS OF LICENSE PLATE:' #VALUE IF #LICENSE = MASK ('NY-'XXXXX) #VALUE
The following condition would be met by any value which
contains NAT
and AL
no matter which and how many
other characters are between NAT
and AL
(this would
include the values NATURAL
and NATIONALITY
as well as
NATAL
):
MASK('NAT'*'AL')
Legacy applications often have packed or unpacked numeric fields
redefined with alphanumeric or binary fields. Such redefinitions are not
recommended, because using the packed or unpacked field in an assignment or
computation may lead to errors or unpredictable results. To validate the
contents of such a redefined field before the field is used, enter an
N
for each digit of the field (counting the digits before and
after the decimal point), minus one, followed by a Z
(see
Characters in a
Mask).
IF #P1 (P1) = MASK (Z) IF #N4 (N4) = MASK (NNNZ) IF #P5 (P5) = MASK (NNNNZ) IF #P32 (P3.2) = MASK (NNNNZ)
For further information about checking field contents, see MASK Option Compared with IS Option.
This section points out the difference between the MASK
option and the IS
option and contains a sample program to
illustrate the difference.
The IS
option can be used to check whether the content
of an alphanumeric or Unicode field can be converted to a specific other
format, but it cannot be used to check if the value of an alphanumeric field is
in the specified format.
The MASK
option can be used to validate the contents of
a redefined packed or unpacked numeric variable.
** Example 'LOGICX09': MASK versus IS option in logical condition ************************************************************************ DEFINE DATA LOCAL 1 #A2 (A2) 1 REDEFINE #A2 2 #N2 (N2) 1 REDEFINE #A2 2 #P3 (P3) 1 #CONV-N2 (N2) 1 #CONV-P3 (P3) END-DEFINE * #A2 := '12' WRITE NOTITLE 'Assignment #A2 := "12" results in:' PERFORM SUBTEST #A2 := '-1' WRITE NOTITLE / 'Assignment #A2 := "-1" results in:' PERFORM SUBTEST #N2 := 12 WRITE NOTITLE / 'Assignment #N2 := 12 results in:' PERFORM SUBTEST #N2 := -1 WRITE NOTITLE / 'Assignment #N2 := -1 results in:' PERFORM SUBTEST #P3 := 12 WRITE NOTITLE / 'Assignment #P3 := 12 results in:' PERFORM SUBTEST #P3 := -1 WRITE NOTITLE / 'Assignment #P3 := -1 results in:' PERFORM SUBTEST * DEFINE SUBROUTINE SUBTEST IF #A2 IS (N2) THEN #CONV-N2 := VAL(#A2) WRITE NOTITLE 12T '#A2 can be converted to' #CONV-N2 '(N2)' END-IF IF #A2 IS (P3) THEN #CONV-P3 := VAL(#A2) WRITE NOTITLE 12T '#A2 can be converted to' #CONV-P3 '(P3)' END-IF IF #N2 = MASK(NZ) THEN WRITE NOTITLE 12T '#N2 contains the valid unpacked number' #N2 END-IF IF #P3 = MASK(NNZ) THEN WRITE NOTITLE 12T '#P3 contains the valid packed number' #P3 END-IF END-SUBROUTINE * END
Output of Program LOGICX09
:
Assignment #A2 := '12' results in: #A2 can be converted to 12 (N2) #A2 can be converted to 12 (P3) #N2 contains the valid unpacked number 12 Assignment #A2 := '-1' results in: #A2 can be converted to -1 (N2) #A2 can be converted to -1 (P3) Assignment #N2 := 12 results in: #A2 can be converted to 12 (N2) #A2 can be converted to 12 (P3) #N2 contains the valid unpacked number 12 Assignment #N2 := -1 results in: #N2 contains the valid unpacked number -1 Assignment #P3 := 12 results in: #P3 contains the valid packed number 12 Assignment #P3 := -1 results in: #P3 contains the valid packed number -1
Syntax:
operand1
[NOT ] MODIFIED
|
This option is used to determine whether the content of a field has
been modified during the execution of an INPUT
or
PROCESS PAGE
statement. As a precondition, a control variable must have been assigned using
the parameter CV
.
Operand Definition Table:
Operand | Possible Structure | Possible Formats | Referencing Permitted | Dynamic Definition | |||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
operand1
|
S | A | C | no | no |
Attribute control variables referenced in an INPUT
or
PROCESS PAGE
statement are always assigned the status "not
modified" when the map is transmitted to the terminal.
Whenever the content of a field referencing an attribute control variable is modified, the attribute control variable has been assigned the status "modified". When multiple fields reference the same attribute control variable, the variable is marked "modified" if any of these fields is modified.
If operand1
is an array, the
result will be true if at least one of the array elements has been assigned the
status "modified" (OR
operation).
The Natural profile parameter
CVMIN
may
be used to determine if an attribute control variable is also to be assigned
the status "modified" if the value of the corresponding field is
overwritten by an identical value.
** Example 'LOGICX06': MODIFIED option in logical condition ************************************************************************ DEFINE DATA LOCAL 1 #ATTR (C) 1 #A (A1) 1 #B (A1) END-DEFINE * MOVE (AD=I) TO #ATTR * INPUT (CV=#ATTR) #A #B IF #ATTR NOT MODIFIED WRITE NOTITLE 'FIELD #A OR #B HAS NOT BEEN MODIFIED' END-IF * IF #ATTR MODIFIED WRITE NOTITLE 'FIELD #A OR #B HAS BEEN MODIFIED' END-IF * END
Output of Program LOGICX06
:
#A #B
After entering any value and pressing ENTER, the following output is displayed:
FIELD #A OR #B HAS BEEN MODIFIED
Syntax:
operand1 |
|
SCAN
|
operand2 |
Operand Definition Table:
Operand | Possible Structure | Possible Formats | Referencing Permitted | Dynamic Definition | |||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
operand1
|
C | S | A | N | A | U | N | P | yes | no | |||||||||||
operand2
|
C | S | A | U | B* | yes | no |
* operand2
may
only be binary if operand1
is of format
A or U. If operand1
is of format U and
operand2 is of format B, then the length of
operand2
must be even.
The SCAN
option is used to scan for a specific value
within a field.
The characters used in the SCAN
option
(operand2
) may be specified as an
alphanumeric or Unicode constant (a character string bounded by apostrophes) or
the contents of an alphanumeric or Unicode database field or user-defined
variable.
Caution:
Trailing blanks are automatically eliminated from
operand1
and
operand2
. Therefore, the
SCAN
option cannot be used to scan for values containing trailing
blanks. operand1
and
operand2
may contain leading or
embedded blanks. If operand2
consists
of blanks only, scanning will be assumed to be successful, regardless of the
value of operand1
; confer
EXAMINE
FULL
statement if trailing blanks are not to be ignored in
the scan operation.
The field to be scanned
(operand1
) may be of format A, N, P or
U. The SCAN
operation may be specified with the equal
(EQ
) or not equal (NE
) operators.
The length of the character string for the SCAN
operation should be less than the length of the field to be scanned. If the
length of the character string specified is identical to the length of the
field to be scanned, then an EQUAL
operator should be used instead
of SCAN
.
** Example 'LOGICX02': SCAN option in logical condition ************************************************************************ DEFINE DATA LOCAL 1 EMPLOY-VIEW VIEW OF EMPLOYEES 2 NAME * 1 #VALUE (A4) 1 #COMMENT (A10) END-DEFINE * INPUT 'ENTER SCAN VALUE:' #VALUE LIMIT 15 * HISTOGRAM EMPLOY-VIEW FOR NAME RESET #COMMENT IF NAME = SCAN #VALUE MOVE 'MATCH' TO #COMMENT END-IF DISPLAY NOTITLE NAME *NUMBER #COMMENT END-HISTOGRAM * END
Output of Program LOGICX02
:
ENTER SCAN VALUE:
A scan for example for LL
delivers three matches in 15
names:
NAME NMBR #COMMENT -------------------- --------- ---------- ABELLAN 1 MATCH ACHIESON 1 ADAM 1 ADKINSON 8 AECKERLE 1 AFANASSIEV 2 AHL 1 AKROYD 1 ALEMAN 1 ALESTIA 1 ALEXANDER 5 ALLEGRE 1 MATCH ALLSOP 1 MATCH ALTINOK 1 ALVAREZ 1
Syntax:
parameter-name [NOT ] SPECIFIED
|
This option is used to check whether an optional parameter in an invoked object (subprogram or external subroutine) has received a value from the invoking object or not.
An optional parameter is a field defined with the keyword
OPTIONAL
in the
DEFINE DATA
PARAMETER
statement of the invoked object. If a field is
defined as OPTIONAL
, a value can - but need not - be passed from
an invoking object to this field.
In the invoking statement, the notation
nX
is used to indicate parameters for
which no values are passed.
If you process an optional parameter which has not received a value,
this will cause a runtime error. To avoid such an error, you use the
SPECIFIED
option in the invoked object to check whether an
optional parameter has received a value, and then only process it if it
has.
parameter-name
is the name
of the parameter as specified in the DEFINE DATA PARAMETER
statement of the invoked object.
For a field not defined as OPTIONAL
, the
SPECIFIED
condition is always TRUE
.
Calling Programming:
** Example 'LOGICX07': SPECIFIED option in logical condition ************************************************************************ DEFINE DATA LOCAL 1 #PARM1 (A3) 1 #PARM3 (N2) END-DEFINE * #PARM1 := 'ABC' #PARM3 := 20 * CALLNAT 'LOGICX08' #PARM1 1X #PARM3 * END
Subprogram Called:
** Example 'LOGICX08': SPECIFIED option in logical condition ************************************************************************ DEFINE DATA PARAMETER 1 #PARM1 (A3) 1 #PARM2 (N2) OPTIONAL 1 #PARM3 (N2) OPTIONAL END-DEFINE * WRITE '=' #PARM1 * IF #PARM2 SPECIFIED WRITE '#PARM2 is specified' WRITE '=' #PARM2 ELSE WRITE '#PARM2 is not specified' * WRITE '=' #PARM2 /* would cause runtime error NAT1322 END-IF * IF #PARM3 NOT SPECIFIED WRITE '#PARM3 is not specified' ELSE WRITE '#PARM3 is specified' WRITE '=' #PARM3 END-IF END
Output of Program LOGICX07
:
Page 1 14-01-14 11:25:41 #PARM1: ABC #PARM2 is not specified #PARM3 is specified #PARM3: 20