TOPS-20 PASCAL Language Manual - Bitsavers

PROGRAM HEADING AND DECLARATION SECTION
4.3 CONSTANT DEFINITIONS
The constant section defines identifiers to represent constant values.
Fo rma t
CONST constant name
value; [constant name value; II
where:
constant name
value
specifies the identifier to be used as the
name of the constant.
specifies an jnteger, a real number, a
string, a Boo]ean va]ue, or the name of
another constant that is already defined.
Note that the value assigned to a constant
identifier cannot be an expression. String
values must be enclosed in apostrophes.
The use of constant identifiers generally makes a program easier to
read, understand, and modify. If you need to change the value of a
constant, you can simply modify the CONST declaration instead of
changing each occurrence of the value in the program. This capability
makes programs simpler to maintain and easier to transport.
Example
CON~)T Ra i n ~:: TRUE,
Y to" a T' ~~ 20 O:L ,
Pi ::: 3 .l4:1.!:j92?'
C () ITlIT! a:;:: ',' p
Countr~ = 'United States';
Citizenship = Country;
This CONST section defines six constants. The identifier Rain is
equal to the Boolean value TRUE. The identifier Year represents an
integer, and Pi represents the real number 3.1415927. The identifier
Comma represents a character, and the identifier Country represents a
string. Characters and strings must be enclosed in apostrophes in the
CONST section. The identifier Citizenship represents the symbolic
constant Country and thus repr~sents a character string. Note that,
since Citizenship represents a symbolic value and not a string,
apostrophes are not used.
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