CHAPTER 14: Blocks and Statements

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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.