[Firebird-docs] Talking' about precedence...

[Paul Vinkenoog]

Hi all (especially Helen),

I got suspicious when I saw the precedence of arithmetic operators listed like this:

1: *
2: /
3: +
4: -

So I tested it:

SQL> select 1 - 3 + 3 from rdb$database;

ADD
=====================
1

-- so + doesn't have higher precedence than - (otherwise result would be -5)

SQL> select 2.0 / 8.0 * 10.0 from rdb$database;

MULTIPLY
=====================
2.500

-- so * doesn't have higher precedence than / (otherwise result would be 0.025)


SQL> select 4 + 5 * 10 from rdb$database;

ADD
=====================
54

-- as expected, * has higher precedence than + (otherwise result would be 90)

SQL> select 5.0 + 5.0 / 5.0 from rdb$database;

ADD
=====================
6.00

-- as expected, / has higher precedence than + (otherwise result would be 2.00)

So the correct order is:

1: *, /
2: +, -

Operators of the same precedence are evaluated LTR.


Cheers,
Paul