if
StatementThe if
statement allows conditional execution of a statement or a conditional choice of two statements, executing one or the other but not both.
IfThenStatement:
if (
Expression)
Statement IfThenElseStatement:
if (
Expression)
StatementNoShortIfelse
Statement IfThenElseStatementNoShortIf:
if (
Expression)
StatementNoShortIfelse
StatementNoShortIf
The Expression must have type boolean
, or a compile-time error occurs.
if-then
StatementAn if
-then
statement is executed by first evaluating the Expression. If evaluation of the Expression completes abruptly for some reason, the if
-then
statement completes abruptly for the same reason. Otherwise, execution continues by making a choice based on the resulting value:
true
, then the contained Statement is executed; the if
-then
statement completes normally only if execution of the Statement completes normally.false
, no further action is taken and the if
-then
statement completes normally.if-then-else
StatementAn if
-then
-else
statement is executed by first evaluating the Expression. If evaluation of the Expression completes abruptly for some reason, then the if
- then
-else
statement completes abruptly for the same reason. Otherwise, execution continues by making a choice based on the resulting value:
true
, then the first contained Statement (the one before the else
keyword) is executed; the if
-then
-else
statement completes normally only if execution of that statement completes normally.false
, then the second contained Statement (the one after the else
keyword) is executed; the if
-then
-else
statement completes normally only if execution of that statement completes normally.