Compaq AA-PWCBD-TE manual Example 4-9 Procedure That Uses the Case Statement

Lexical Elements of the DEC Text Processing Utility Language 4.9 Reserved Words

Syntax

CASE case-selector [[FROM lower-constant-expr, TO upper-constant-expr]]

[constant-expr_1 [[,...]]] : statement [[,...]];

[constant-expr_2 [[,...]]] : statement [[,...]];

.

.

.

[constant-expr_n[[,...]]] : statement [[,...]];

[[[INRANGE] : statement [[,...]] ;]]

[[[OUTRANGE] : statement [[,...]] ;]]

ENDCASE;

The single brackets are not optional for case constants. Example 4–9 shows how to use the CASE statement in a procedure.

CASE constant expressions must evaluate at compile time to either a keyword, a string constant, or an integer constant. All constant expressions in the CASE statement must be of the same data type. There are two special case constants in DECTPU: INRANGE and OUTRANGE. INRANGE matches anything that falls within the case range that does not have a case label associated with it. OUTRANGE matches anything that falls outside the case range. These special case constants are optional.

FROM and TO clauses of a CASE statement are not required. If FROM and TO clauses are not specified, INRANGE and OUTRANGE labels refer to data between the minimum and maximum specified labels.

Example 4–9 shows a sample procedure that uses the CASE statement.

Example 4–9 Procedure That Uses the CASE Statement

PROCEDURE grades

answers := READ_LINE ("Enter number of correct answers:",5); answers := INT (answers);

CASE answers FROM 0 TO 10

[10]: score := "A+";

[9]: score := "A";

[8]: score := "B";

[7]: score := "C";

[6]: score := "D";

[0,1,2,3,4,5] : score := "F";

[OUTRANGE] : score := "Invalid entry.";

ENDCASE;

MESSAGE (score);

ENDPROCEDURE;

This CASE statement compares the value of the constant selector answers to the case labels (the numbers 0 through 10). If the value of answers is any of the numbers from 0 through 10, the statement to the right of that number is executed. If the value of answers is outside the range of 0 through 10, the statement to the right of [OUTRANGE] is executed. The value of score is written in the message area after the execution of the CASE statement.

4–22Lexical Elements of the DEC Text Processing Utility Language