IF

[ if _label : ]
    if condition then
        sequence_of_statements
    { elsif condition then
        sequence_of_statements }
    [ else
        sequence_of_statements ]
end if [ if _label ] ;

• function_statement_part
• procedure_statement_part
• process_statement_part

• identifier

boolean _expression

{ sequential_statement }

If a has the value 1 then b is assigned the value 0 .

IF a = '1' THEN
   b := '0' ;
END IF ;

If the value of a is bigger than 0 then b is assigned the value of a, otherwise that of ABS ( a + 1 ).

IF a > 0 THEN
   b := a ;
ELSE
   b := ABS ( a + 1 ) ;
END IF ;

This is an example of a complete IF - ELSIF -loop. The conditions are checked one after the other. When the first match is found the relevant actions are carried out and the IF -loop is left.

IF val >= 5 AND val < 10 THEN
   int := 7 ;
ELSIF val < 5 THEN
   int := val + func( val + 2 ) ;
ELSIF val < 15 THEN
   int := func( val ) ;
ELSE
   int := 0 ;
END IF ;