Datatype promotion when evaluating numeric expressions – PB Docs 126

Datatypes of operands

If operands in an expression have different datatypes, the
value whose type has lower precedence is converted to the datatype
with higher precedence.

Unsigned versus signed

Unsigned has precedence over signed, so if one operand is
signed and the other is unsigned, both are promoted to the unsigned version
of the higher type. For example, if one operator is a long and
another UnsignedInteger, both are promoted
to UnsignedLong.

Operators

The effects of operators on an expression’s datatype
are:

• +,
  -, *

  The minimum precision for addition, subtraction, and multiplication
  calculations is long. Integer types
  are promoted to long types before doing the
  calculation and the expression’s resulting datatype is,
  at a minimum, long. When operands have datatypes
  of higher precedence, other operands are promoted to match based
  on the Datatypes of operands rule above.

• / and ^

  The minimum precision for division and exponentiation is double.
  All types are promoted to double before doing
  the calculation, and the expression’s resulting datatype
  is double.

• Relational

  Relational operators do not cause promotion of numeric types.

Integer literals beyond the range of LongLong cause
compiler errors.