TOPS-20 PASCAL Language Manual - Bitsavers

PASCAL STATEMENTS
Example 1
CASE
END;
Alphabetic OF
'A','E','I'p'O','U' : Alpha_Fla~ := Vowel~
"~(I : Alpha .... Fla~:,~ != SometimE-'s
OTHERWISE Alpha_Flag := Consonant
This example assigns a value to Alpha Flag depending on the value of
the character variable Alphabetic.
5.4 REPETITIVE STATEMENTS
Repetitive statements specify loops, that is, the repetitive execution
of one or more statements. PASCAL provides three repetitive
sta tements:
• FOR statement
• REPEAT statement
• WHILE statement
These are described in the following sections.
5.4.1 The FOR Statement
The FOR statement specifies the repetitive execution of a statement
based on the value of an automatically incremented or decremented
control variable.
Forma t
FOR control variable
-= initial value {TO } final value DO statement;
DOWNTO
where:
control variable
initial value
final value
specifies the name of a simple variable of
any scalar type except a real type.
specifies an expression of the same type as
the control variable.
specifies an expression of the same type as
the control variable.
The control variable, the initial value, and the final value must all
be of the same scalar type, but cannot belong to one of the real
types. The repeated statement cannot change the value of the control
variable. The control variable must be a simple variable; that is,
it cannot be an element of an array, a field of a record, the object
of a pointer reference, or a file buffer variable.
At run time, completion tests are performed before the statement is
executed. In the TO form, if the value of the control variable is
less than or equal to the final value, the loop is executed, and the
control variable is incremented. When the value of the control
variable is greater than the final value, execution of the loop is
complete.
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