Mega Code Archive
Boolean - allows just true and false values
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type Boolean = (False, True);
Description
The Boolean type provides an enumeration of the logical True and False values.
Unlike other languages, it is not a number - it will only allow these values. This makes the code much more reliable.
Notes
Using calculations to test for true or false is a C like practice, but is supported in Delphi. Use the following to hold such a logical number:
ByteBool
WordBool
LongBool
Related commands
And Boolean and or bitwise and of two arguments
If Starts a conditional expression to determine what to do next
Not Boolean Not or bitwise not of one arguments
Or Boolean or or bitwise or of two arguments
Xor Boolean Xor or bitwise Xor of two arguments
Example code : Boolean assignments and tests
var
same : Boolean;
small, large, i : Integer;
begin
small := 23;
large := 455555;
// Test directly to see if these numbers are the same size
if small = large
then ShowMessage('small = large')
else ShowMessage('small <> large');
// Use a Boolean to hold and test this outcome
same := (small = large);
if same
then ShowMessage('small = large')
else ShowMessage('small <> large');
// Assign a direct logical value to this Boolean
same := True;
if same
then ShowMessage('same is True')
else ShowMessage('same is False');
end;
Show full unit code
small <> large
small <> large
same is True
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