# Selection

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## Logic expressions

With the different versions of the selection statement (the if statement, that is), you can use logic expressions to control the program flow.

A logic expression can use the following operators:

 Symbol Example Meaning = a = b true if expression a is equal to expression b <> a <> b true if a is not equal to be < a < b true if a is less than b > a > b true if a is greater than b <= a <= b true if a is less than or equal to b >= a >= b true if a is greater than or equal to b and a and b true if expression a and b are both true or a or b true if expression a, b or both are true

During evaluation the operators have the following priorities (highest first):

*
/, %
+, -
=, <>, <, >, <=, >=
and, or

, where % is the modulus operator. But, of course, parenthesis can be used to force precendence.

## If and then

if logic expr then statement

If the logic expression evaluates to true, the one statement is performed.

## If and endif

if logic expr
statement
...
endif

If the logic expression evaluates to true, all the statements between the if and endif lines are performed.

## If, else and endif

if logic expr
statement
...
else
statement
...
endif

If the logic expression evaluates to true, the statements between the if and else lines are performed, else the statements between else and endif are performed.

## If, elseif, else and endif

if logic expr
statement
...
elseif logic expr
statement
...
...
[else
statement
...]
endif

If the first expression evaluates to true, the statements between if and elseif are performed. Else the second expression is evaluated to se if the lines between elseif and another elseif, else or endif are to be performed.

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