The IF - ELSE branch

The following control statements are used for IF-ELSE branches:

$IF, $ELSE, $ELSIF, $ENDIF.

Branching always starts with

$IF <expr>

and always ends with

$ENDIF

Control statements

 

$ELSE
and
$ELSEIF

 

are optional and serve to set up multiple branches.

Attention

attention

The condition in the $IF control block is checked by verifying the mathematical expression for "true” or "not true” (TRUE and FALSE). To be able to also use decimal variables, the jump condition is regarded as fulfilled (TRUE) if...

...the absolute value of the mathematical expression is > or = 0.5.

Programing Example

prg_example

The IF - ELSE branch

N10 ...

N20 $IF P1      Only if |P1| is greater or equal to 0.5 are the
statements N30 to N50 executed.

N30 ...

N40

N50

N60 $ENDIF

However, the following is also possible :

N10 ...

N20 $IF P1 >= 0.5    Only if P1 is greater or equal to 0.5 are the

                     statements N30 to N50 executed.

N30 ...

N40

N50

N60 $ENDIF

or:

N10 ...

N20 $IF P1 > P2      Only if P1 is greater than P2, are the statements
                     N30 to N50 executed, otherwise the statements N70 to N90

N30 ...

N40 ...

N50 ...

N60 $ELSE

N70 ...

N80 ...

N90 ...

N100 $ENDIF

These use of ELSEIF permits:

N10 ...

N20 $IF P1 == 0     Only if P1 is equal to 0, are the statements N30 to N50
                    executed, otherwise the $ELSEIF condition is
                    checked whether P2 >= 0.5 and
                    accordingly N70 to N90 or N110 to N130 are executed.

N30 ...

N40

N50

N60 $ELSEIF P2>=0.5 The $ELSEIF condition is used
                     To set up branching nested in one another.

N70 ...

N80

N90

N100 $ELSE

N110 ...

N120

N130

N140 $ENDIF

Attention

attention

The C programming language also makes a distinction in syntax between

Assignment : P5 = 3

and

Comparison: $IF P5 == 3

The following applies to Version 2.3 and earlier: As mathematical expressions expect always the sequence…

Operator -> Term -> Operator -> Term -> etc.

…expressions preceded by a minus sign must be bracketed in comparison operation ("-" is interpreted as operator).

Programing Example

prg_example

$IF P1 >= -5     wrong because term->operator->operator->term

$IF P1 >= [-5]   right because term->operator->term->operator->term