HP 3000 Manuals HP 3000 Manuals
WHILE
Repeatedly tests a condition clause and executes a simple or compound
statement while the condition is true.
Syntax
WHILE condition-clause statement;
WHILE causes Transact to test a condition-clause. The condition clause
includes one or more conditions, each made up of a test-variable, a
relational-operator, and one or more values; multiple conditions are
joined by AND or OR. If the result of that test is true, then the
statement following the condition is executed. Then the condition clause
is tested again and the process repeated while the result of the test is
true. When the result of the test is false, control passes to the
statement following the WHILE statement.
Statement Parts
condition- One or more conditions, connected by AND or OR, where
clause
AND A logical conjunction. The condition clause
is true if all of the conditions are true; it
is false if one of the conditions is false.
OR A logical inclusive OR. The condition clause
is true if any of the conditions is true; it
is false if all of the conditions are false.
Each condition contains a test-variable,
relational-operator, and one or more values in the
following format:
test-variable relational-operator value [,value]...
test- Can be one or more of the following:
variable
(item-name The value in the data register that
[(sub- corresponds to item-name. The item-name can
script)]) be subscripted if an array item is being
referenced. (See "Array Subscripting" in
Chapter 3.)
[arithmetic An arithmetic expression containing item
expression] names and/or constants. The expression is
evaluated before the comparison is made.
(See the LET verb for more information.)
____________________________________________
NOTE An arithmetic-expression must be
enclosed in square brackets ([ ]).
____________________________________________
EXCLA- Current status of the automatic
MATION null response to a prompt set
by a user responding with an
exclamation point (!) to a
prompt. (See "Data Entry
Control Characters" in Chapter
5.) If the null response is
set, the EXCLAMATION test
variable is a positive integer;
if not set, it is zero. The
default is 0.
FIELD Current status of FIELD command
qualifier. If a user qualifies
a command with FIELD, the FIELD
test variable is a positive
integer. Otherwise, it is a
negative integer. The default
is < 0.
INPUT The last value input in
response to the INPUT prompt.
PRINT Current status of PRINT or
TPRINT command qualifier. If a
user qualifies a command with
PRINT, the PRINT test variable
is an integer greater than zero
and less than 10; if a command
is qualified with TPRINT, PRINT
is an integer greater than 10;
if neither qualifier is used,
PRINT is a negative integer.
The default is <0.
REPEAT Current status of REPEAT
command qualifier. If a user
qualifies a command with
REPEAT, the REPEAT test
variable is a positive integer;
otherwise, REPEAT is a negative
integer. The default is < 0.
SORT Current status of SORT command
qualifier. If a user qualifies
a command with SORT, the value
of the SORT test variable is a
positive integer; otherwise
SORT is a negative integer.
The default is < 0.
STATUS The value of a 32-bit integer
register set by the last data
set or file operation, data
entry prompt, or external
procedure call.
relational- Specifies the relation between the test-variable and the
operator values. It can be one of the following:
= equal to
<> not equal to
< less than
<= less than or equal to
> greater than
>= greater than or equal to
value The value against which the test-variable is compared. The
value can be an arithmetic expression, which will be
evaluated before the comparison is made. The allowed value
depends on the test variable, as shown in the comparison
below. Alphanumeric strings must be enclosed in quotation
marks.
If the test- The value must be:
variable
is:
item-name An alphanumeric string, a numeric value, an
arithmetic expression, a reference to a
variable as in (item-name), or a class
condition as described below.
[arithmetic A numeric value, an arithmetic expression, or
expression] an expression, or a reference to a variable
as in (item-name).
INPUT An alphanumeric string.
EXCLA- A positive or negative
MATION integer, or an expression.
FIELD
PRINT
REPEAT
SORT
STATUS A 32-bit integer or expression.
Alphanumeric strings must be enclosed in quotation marks.
If more than one value is given, then:
* The relational-operator can be only "=" or "<>".
* When the relational operator is "=", the action is
taken if the test-variable is equal to value1 OR
value2 OR...valuen. In other words, a comma in a
series of values is interpreted as an OR.
* When the relational operator is "<>", the action is
taken if the test-variable is not equal to value1
AND value2 AND...valuen.
In other words, a comma in a series of values is
interpreted as an AND when the operator is "<>".
When the test variable is an item-name, the value can be
one of the following class conditionals, which are used to
determine whether a string is all numeric or alphabetic.
The operator can only be "=" or "<>".
NUMERIC This class condition includes the ASCII
characters 0 through 9 and a single
operational leading sign. Leading and
trailing blanks around both the number and
sign are ignored. Decimal points are not
allowed in NUMERIC data. This class test is
only valid when the item has the type X, U,
9, or Z, or when the item is in the input
register.
ALPHABETIC This class condition includes all ASCII
native language alphabetic characters (upper
and lowercase) and space. This class test
is only valid for item names of type X or U.
ALPHABETIC- This class condition includes all ASCII
LOWER lowercase native language alphabetic
characters and space. This class test is
only valid for item names of type X or U.
ALPHABETIC- This class condition includes all ASCII
UPPER uppercase native language alphabetic
characters and space. This class test is
only valid for item names of type X or U.
statement Any simple or compound Transact statement; a compound
statement is one or more statements bracketed by a DO/DOEND
pair.
Order of Evaluation
When complex conditions are included, the operator precedence is:
* Arithmetic expressions are evaluated.
* Truth values are established for simple relational conditions.
* Truth values are established for simple class conditions.
* Multiple value conditions are evaluated.
* Truth values are established for complex AND conditions.
* Truth values are established for complex OR conditions.
Parentheses can be used to control the order of precedence when
conditional clauses are being evaluated. In multiple value conditions,
evaluation terminates as soon as a truth value is determined.
Examples
WHILE (SUB-TOTAL) >= 0
DO
GET(CHAIN) ORDERS;
.
.
.
LET (SUB-TOTAL)=(SUB-TOTAL) - (OUT-BAL);
DOEND;
WHILE (BALANCE) < 0 AND STATUS 0
DO
GET(CHAIN) CUST-DETAIL,STATUS;
LET (BALANCE) = (BALANCE) + (AMOUNT);
DOEND;
WHILE (PART-NO-PREFIX) <> (PROTOTYPE),(DEVELOPMENT)
GET(CHAIN) PART-DETAIL,STATUS;
The next example sorts the entries in data set ORDER-DET in primary
sequence by ORD-NO and in secondary sequence by PROD-NO. As it sorts, it
passes the sorted entries to the PERFORM statements at the label DISPLAY
to be displayed in sorted order.
SORT-FILE:
LIST ORD-NO:
PROD-NO:
DESCRIPTION:
QTY-ORD:
SHIP-DATE:
FIND(SERIAL) ORDER-DET,
LIST=(ORD-NO:SHIP-DATE),
SORT=(ORD-NO,PROD-NO),
PERFORMDISPLAY;
.
.
DISPLAY:
DISPLAY "Order List by Product Number", LINE2:
ORD-NO, NOHEAD, COL5:
PROD-NO, NOHEAD, COL20:
QTY-ORD, NOHEAD, COL35:
SHIP-DATE, NOHEAD, COL50;