Operator priority

Operator priority is evaluated in two steps: firstly, by the order of precedence of operator types; secondly, within an operator type by the order of precedence for operators.

Order of precedence for “operator types”:

1. Sign, negation

2. Arithmetic operators

3. Concatenation operator

4. Relational operators

5. Logical operators

Order of precedence for arithmetic operators (“Dot operations before line operations”):

1. Multiplication, division, modulo operation (*, /, MOD)

2. Addition, subtraction (+, -)

Order of precedence for logical operators:

1. AND operation (AND)

2. OR operation (OR, XOR)

Relational operators:
All relational operators have the same order of precedence.

Example

Complex logical expressions are often used in IF blocks in the CONDITION operand of the IF command. If the condition determined by the expression is true, the command that follows the IF command is processed. If the condition is false, the next ELSE-IF or ELSE command is processed (for more information on IF, ELSE-IF, and ELSE commands, see chapter “Creating S procedures” or chapter “SDF-P commands” ).

For example, an IF command could contain the following condition:

A + B / C > D + C MOD E AND A + D * E < D * C OR F // G > H

At the time of the IF query, variables A to H have the following values:

/A = 4
/B = 29
/C = 9
/D = 3
/E = 5
/F = 'ABC'
/G = 'DEF'
/H = 'ABCDE'

The expression is evaluated in the following steps:

1. Arithmetic operators: Multiplication / division

   Operation	Corresponds to	Result
   B / C	29 / 9	3
   C MOD E	9 MOD 5	4
   D * E	3 * 5	15
   D * C	3 * 9	27

   Results of step 1:
   A + 3 > D + 4 AND A + 15 < 27 OR F // G > H

2. Arithmetic operators: Addition

   Operation	Corresponds to	Result
   A + 3	4 + 3	7
   D + 4	3 + 4	7
   A + 15	4 + 15	19

   Results of step 2:
   7 > 7 AND 19 < 27 OR F // G > H

3. Concatenation operator

   Operation	Corresponds to	Result
   F // G	'ABC' // 'DEF'	'ABCDEF'

   Results of step 3:
   7 > 7 AND 19 < 27 OR 'ABCDEF' > H

4. Relational operators

   Operation	Result
   7 > 7	FALSE
   19 < 27	TRUE
   'ABCDEF' > 'ABCDE'	TRUE

   Results of step 4:
   FALSE AND TRUE OR TRUE

5. Logical operators: AND

   Operation	Result
   FALSE AND TRUE	FALSE

   Results of step 5:
   FALSE OR TRUE

6. Logical operators: OR

   Operation	Result
   FALSE OR TRUE	TRUE

   Results of step 6:
   TRUE

   Thus, the condition is fulfilled.

Order of evaluation

The order of evaluation is not defined for any operands. It can occur that the right operand of an AND operation is evaluated first.

Example

/DECLARE-VARIABLE I(TYPE = INTEGER)

/IF IS-INITIALIZED ('I') AND (I < 10)

Since, at this time, I is not yet initialized, evaluating I < 10 results in an error.