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if Boolean_expression then statementor with an alternative statement:
if Boolean_expression then statement1 else statement2
The if ... then statement executes statement1 depending
on Boolean expression being true. If else is specified, it
continues executing statement2 instead.
if is defined in ISO 7185 Pascal and supported
by all Pascal variants.
program IfDemo;
var
Foo, Bar: Boolean;
begin
Foo := True;
Bar := False;
if ((1 = 1) or (2 = 3)) and (Foo = not Bar) then
begin
{ This is executed if either Foo is true but not Bar or vice versa }
WriteLn ('Either Foo or Bar is true.');
if Bar then
WriteLn ('You will see this text if Bar is true.')
end
else { This whole `else' branch is not executed }
if 1 = 1 then
if True = False then
WriteLn ('This text is never written on screen.')
else { Note: This ``else'' belongs to ``if True = False'' }
WriteLn ('This text is never written on screen as well.')
else { Note: This ``else'' belongs to ``if 1 = 1'' }
WriteLn ('Nor is this.')
end.