Mega Code Archive
Set - defines a set of up to 255 distinct values
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1 type Name = Set of Ordinal type;
2 type Name = Set of Value range;
Description
The Set keyword defines an set type for up to 255 discrete values. Do not confuse with enumerations - they can only adopt one value. A set variable always holds all set values - some are set on, some are set off.
The Ordinal type can be :
Characters such as 'A' and '5'
Integers in the range 0 to 255
Enumerations names such as Diamonds, Clubs
Remember that a Set declaration is a variable. As such, it has all possible values set off at the start.
When you initialise the set, you will be setting some or all of these values on.
You can then check a variable to see if its value is in the set. You might want to do this, for example, when parsing code, to see if the next character is a lower case letter.
Notes
Each enumeration type, or set member, occupies one bit of a 256 bit (32 byte) mask.
Any of these 32 bytes that contains none of the enumeration definition bits is omitted from the set in order to save storage. See the examples for an illustration of this.
Related commands
Exclude Exclude a value in a set variable
In Used to test if a value is a member of a set
Include Include a value in a set variable
Example code : Sets of characters
var
Alphabet : Set of 'A'..'z'; // Set of all letters
begin
Alphabet := ['A'..'z']; // Set all of the members ON
// Check values against the alphabet set
if 'Z' in Alphabet
then ShowMessage('Z is in Alphabet')
else ShowMessage('Z is NOT in Alphabet');
if 'd' in Alphabet
then ShowMessage('d is in Alphabet')
else ShowMessage('d is NOT in Alphabet');
if '1' in Alphabet
then ShowMessage('1 is in Alphabet')
else ShowMessage('1 is NOT in Alphabet');
end;
Show full unit code
Z is in Alphabet
d is in Alphabet
1 is NOT in Alphabet
Example code : Sets of positive numbers
var
SmallNums : Set of 0..55; // Set of the first 56 set members
LargeNums : Set of 200..255; // Set of the last 56 set members
FullNums : Set of 0..255; // Set of the all 256 set members
begin
// We have a range of 0 to 55 values that we can set
// Notice the great flexibility we have in setting values
// We can specify multiple ranges, and individual members
SmallNums := [3..12,23,30..32]; // Set only some of the members on
// Show the storage taken by these sets
// Each set member takes up one bit of one byte of a possible 32 bytes.
// However, only bytes with at least one bit set are stored
ShowMessage('SmallNums uses : '+IntToStr(SizeOf(SmallNums))+' bytes');
ShowMessage('LargeNums uses : '+IntToStr(SizeOf(LargeNums))+' bytes');
ShowMessage('AllNums uses : '+IntToStr(SizeOf(FullNums))+' bytes');
// Check values against the small numbers set
if 12 in SmallNums
then ShowMessage('12 is in SmallNums')
else ShowMessage('12 is NOT in SmallNums');
if 13 in SmallNums
then ShowMessage('13 is in SmallNums')
else ShowMessage('13 is NOT in SmallNums');
if 30 in SmallNums
then ShowMessage('30 is in SmallNums')
else ShowMessage('30 is NOT in SmallNums');
end;
Show full unit code
SmallNums uses : 7 bytes
LargeNums uses : 7 bytes
AllNums uses : 32 bytes
12 is in SmallNums
13 is NOT in SmallNums
30 is in SmallNums
Example code : Sets of user defined enumeration values
type
TNumber = (Ace, One, Two, Three, Four, Five, Siz, Seven, Eight,
Nine, Ten, Jack, Queen, King);
var
CourtCards: Set of TNumber; // Court cards
CardNumbers : array[1..4] of TNumber;
i : Integer;
begin
// Set up the card numbers only to allow picture cards
CourtCards := [Ace, Jack, Queen, King];
// Define some cards
CardNumbers[1] := Ace;
CardNumbers[2] := Four;
CardNumbers[3] := Jack;
CardNumbers[4] := Seven;
// Show the picture cards that we have
for i := 1 to 4 do
if CardNumbers[i] in CourtCards
then ShowMessage('Card '+IntToStr(i)+' is a court card');
end;
Show full unit code
Card 1 is a court card
Card 3 is a court card
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