ການກຳນົດ enumerations
type TSuit = (Hearts, Diamonds, Clubs, Spades); // Defines enumeration range var suit : TSuit; // Defines enumeration variable begin suit := Clubs; // Set to one of the values end;
ການໃຊ້ enumeration numbers
type TDay = (Mon=1, Tue, Wed, Thu, Fri, Sat, Sun); // Enumeration values var today : TDay; weekend : Boolean; begin today := Wed; // Set today to be Wednesday if today > Fri // Ask if it is a weekend day then weekend := true else weekend := false; end;
today is set to Wed which has ordinal value = 3
weekend is set to false since Wed (3) <= Fri (5)
ຕົວຢ່າງ
type TDay = (Mon=1, Tue, Wed, Thu, Fri, Sat, Sun); // Enumeration values var day : TDay; // Enumeration variable begin for day := Mon to Fri do begin // day has each of the values Mon to Fri ( 1 to 5) in 5 iterations // of this loop, allowing you to whatever you want. end; end;
type TSmallNum = 0..9; var smallNum : TSmallNum; begin smallNum := 5; // Allowed smallNum := 10; // Not allowed smallNum := -1; // Not allowed end;
type TUpper = 'A'..'Z'; TLower = 'a'..'z'; TDigit = '0'..'9'; var upper : TUpper; lower : TLower; digit : TDigit; begin upper := 'G'; // Allowed lower := 'g'; // Allowed digit := '7'; // Allowed upper := 'g'; // Not allowed lower := '7'; // Not allowed digit := 4; // Not allowed end;
type TDay = (Mon=1, Tue, Wed, Thu, Fri, Sat, Sun); // Enumeration values TWeekDays = Mon..Fri; // Enumeration subranges TWeekend = Sat..Sun;
ການໃຊ້ Sets
type
TDigits = set of '1'..'9'; // Set of numeric digit characters
var
digits : TDigits; // Set variable
myChar : char;
begin
// At the start, digits has all set values switched off
// So let us switch some on. Notice how we can switch on single
// values, and ranges, all in the one assignment:
digits := ['2', '4'..'7'];
// Now we can test to see what we have set on:
for myChar := '1' to '9' do
if myChar In digits
then ShowMessageFmt('''%s'' is in digits',[myChar])
else ShowMessageFmt('''%s'' is not in digits',[myChar])
end;
ຜົນ
The In operator tests to see if a set contains a value. The ShowMessageFmt function used above displays data in a dialog box. Click on the In and ShowMessageFmt items in the code above to learn more. The data shown is as follows: '1' is not in digits '2' is in digits '3' is not in digits '4' is in digits '5' is in digits '6' is in digits '7' is in digits '8' is not in digits '9' is not in digits
Set operators
+ The union of two sets * The intersection of two sets - The difference of two sets = Tests for identical sets <> Tests for non-identical sets >= Is one set a subset of another <= Is one set a superset of another
type
TNums = set of 1..9;
var
nums1, nums2, nums3, nums4, nums5, nums6 : TNums;
begin
nums1 := [1,2,3];
nums2 := [1,2,4];
nums3 := [1,2,3,4,5,6,7,8,9];
nums4 := nums1 + nums2; // nums4 now [1,2,3,4]
nums5 := nums1 * nums2; // nums5 now [1,2]
nums6 := nums1 - nums2; // nums6 now [3]
// Test for equality
if nums1 = nums2
then ShowMessage('nums1 = nums2')
else ShowMessage('nums1 <> nums2');
// Test for inequality
if nums1 <> nums3
then ShowMessage('nums1 <> nums3')
else ShowMessage('nums1 = nums3');
// Is nums1 a subset of nums3?
if nums1 <= nums3
then ShowMessage('nums1 is a subset of nums3')
else ShowMessage('nums1 is not a subset of nums3');
// Is nums1 a superset of nums3?
if nums1 >= nums3
then ShowMessage('nums1 is a superset of nums3')
else ShowMessage('nums1 is not a superset of nums3');
end;
ຜົນ
nums1 <> nums2 nums1 <> nums3 nums1 is a subset of nums3 nums1 is not a superset of nums3
[tag]Enumeration, SubRanges, Sets, Delphi[/tag]
