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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.