There are four types of selection controls. Namely:

1. IF.....THEN
2. IF.....THEN.....ELSE
3. NESTED IF
4. CASE SECTION

IF....THEN

The IF....THEN selection is used if only one option is available. All other options are ignored

Format:

IF <condition> THEN

    Statements;

ENDIF

Flowchart Sample

IF....THEN....ELSE

This type of selection is suitable where there are two available options

General Format

IF <condition> THEN

    Statements;

ELSE

    Statements;

EndIF

Flowchart Sample

Nested IF Selection

This type of selection is used where two or more options have to be considered to make a selection.

General Format

IF <condition> THEN

statements

ELSE

IF <condition> THEN

statements

ELSE

IF<condition> THEN

Statements

ELSE

Statements

ENDIF

ENDIF

ENDIF

Flowchart Sample

CASE Construct

This is an alternative to the Nested IF especially where there are several options to choose from. Its preferred because it reduces the many lines of code. However, the boolean expression for the case selection can only be expressed using integers and alphabetic characters only. The General format should be

CASE integer OF or

CASE Char OF

Example:

Case x of

label 1: statement 1

label 2: statement 2

label 3: statement 3

.

.

.

label n: statement n-1

Else

statement

Endcase

Selection examples

Selection Questions