Statement-Level Control

BAB VI

Statement-Level Control Structures

Selection Statements

Two- way Selectors (IF Statement)

if control_expression

then clause

else clause

Multiple-way selectors (Switch Case)

Design choices for C’s switch statement

1.       Control expression can be only an integer type

2.       Selectable segments can be statement sequences, blocks, or compound statements

3.       Any number of segments can be executed in one execution of the construct (there is no implicit branch at the end of selectable segments)

4.       default clause is for unrepresented values (if there is no default, the whole statement does nothing).

Iterative Statements

The repeated execution of a statement or compound statement is accomplished either by iteration or recursion.

Counter-Controller Loops

·         A counting iterative statement has a loop variable, and a means of specifying the initial and terminal, and stepsize values.

Logically-Controlled Loops

·         Repetition control is based on a Boolean expression

·         There are posttest and pretest logical controlled loops

·         Posttest logical controlled loop always do the loop a least once. And the statement checked after the looping is done not before.

·         Pretest logical controlled loop test the statement control of the loop, if it’s true then do the loop, if it’s false then stop the looping

User-Located Loop Control Mechanisms

·         Sometimes it is convenient for the programmers to decide a location for loop control (other than top or bottom of the loop).

·         Continue : that skips the remainder of the current iteration, but does not exit the loop

·         Break : Immediately exit the loop.