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Set types

Free Pascal supports the set types as in Turbo Pascal. The prototype of a set declaration is:

_________________________________________________________________________________________________________ Set Types
-- set type set- of- ordinal type------------------------------------
___________________________________________________________________

Each of the elements of SetType must be of type TargetType. TargetType can be any ordinal type with a range between 0 and 255. A set can contain maximally 255 elements. The following are valid set declaration: 

 Type
     Junk = Set of Char;
 
     Days = (Mon, Tue, Wed, Thu, Fri, Sat, Sun);
     WorkDays : Set of days;
Given this set declarations, the following assignment is legal: 
 WorkDays := [ Mon, Tue, Wed, Thu, Fri];
The operators and functions for manipulations of sets are listed in table (3.6).

Table 3.6: Set Manipulation operators
Operation Operator
Union +
Difference -
Intersection *
Add element include
Delete element exclude
Two sets can be compared with the <> and = operators, but not (yet) with the < and > operators. The compiler stores small sets (less than 32 elements) in a Longint, if the type range allows it. This allows for faster processing and decreases program size. Otherwise, sets are stored in 32 bytes.

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