Boolean order of operation in RPGLE

Question

Why does the below code result in true if type = 7 and seq = 224?

RPGLE free form:

if (type = 6 or                 
    type = 7 or                 
    type = 9) and               
    not (seq = 224 or seq=249);

I had to rewrite it to:

if (type = 6 or                 
    type = 7 or                 
    type = 9) and               
    seq <> 224 and 
    seq <> 249;

but why? I am guessing it has something to do with the NOT operator.

Answer 1

Well, NOT has a higher precedence than AND or OR RPG IV Reference manual operator precedence

1. ()
2. Built-in functions, user-defined functions
3. unary +, unary -, NOT
4. **
5. *, /
6. binary +, binary -
7. =, <>, >, >=, <, <=
8. AND
9. OR

However, the expression you show should evaluate to false...

**free

 dcl-s flag ind;
 dcl-s seq int(5) inz(224);
 dcl-s type int(5) inz(7);

   flag = (type = 6 or
           type = 7 or
           type = 9) and
            not (seq = 224 or seq=249);

   dsply ('Flag=' + flag);
   *INLR = *ON;
   return; 

Joblog shows:

DSPLY Flag=0