if
14.8 The if
Statement
The 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 )
StatementNoShortIf else
Statement
IfThenElseStatementNoShortIf:
if (
Expression )
StatementNoShortIf else
StatementNoShortIf
The Expression must have type boolean
, or a compile-time error occurs.
14.8.1 The if-then
Statement
An 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:
- If the value is
true
, then the contained Statement is executed; the if
-then
statement completes normally only if execution of the Statement completes normally.
- If the value is
false
, no further action is taken and the if
-then
statement completes normally.
14.8.2 The if-then-else
Statement
An 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:
- If the value is
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.
- If the value is
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.