If...then...else Statement

Conditionally executes a group ofstatements, depending on the value of anexpression.

Syntax

·        Single line syntax

if condition then statement 

·        Block form syntax

if condition [then] [statement]

[else elsestatements]

endif

·        Block form syntaxusing elseif

if condition [then] [statement]

[elseif elsestatements]

[elseif elsestatements]

[elseif elsestatements]

endif

The if...then...else statement syntax has these parts:

Remarks

You can use the single-line form (first syntax) for short, simple tests. However, the block form (second syntax) provides more structure and flexibility than the single-line form and is usually easier to read, maintain, and debug.Using elseif keyword allows you to avoid having multi-level if...endif statements when you need switch-like logic.

Note:   With the single-line form, it is possible to have multiple statements executed as the result of an if...then decision. All statements must be on the same line and separated by colons, as in the following statement:

inta = 11

ifa>10 then a=a+1

Println(a)

A block form If statement must be the first statement on a line. The else and endif parts of the statement can have only aline number orline labelpreceding them. The block if must end with an endif statement.

To determine whether or not a statement is a block if, examine what follows the then keyword. If anything other than acomment appears after then on the same line, the statement is treated as a single-line if statement.

The else is optional. Block if statements can be nested; that is, contained within one another.