Perl Language Reference Manual by Larry Wall and others Paperback (6"x9"), 724 pages ISBN 9781906966027 RRP £29.95 ($39.95) Sales of this book support The Perl Foundation! Get a printed copy>>> 
6.3 Flavors of Perl numeric operations
Perl operations which take a numeric argument treat that argument in one of four different ways: they may force it to one of the integer/floating/ string formats, or they may behave differently depending on the format of the operand. Forcing a numeric value to a particular format does not change the number stored in the value.
All the operators which need an argument in the integer format treat the
argument as in modular arithmetic, e.g., mod 2**32
on a 32bit
architecture. sprintf "%u", 1
therefore provides the same result as
sprintf "%u", ~0
.
Arithmetic operators

The binary operators
+

*
/
%
==
!=
>
<
>=
<=
and the unary operators
abs
and
will attempt to convert arguments to integers. If both conversions are possible without loss of precision, and the operation can be performed without loss of precision then the integer result is used. Otherwise arguments are converted to floating point format and the floating point result is used. The caching of conversions (as described above) means that the integer conversion does not throw away fractional parts on floating point numbers. ++

++
behaves as the other operators above, except that if it is a string matching the format/^[azAZ]*[09]*\z/
the string increment described in 7 is used. Arithmetic operators during
use integer

In scopes where
use integer;
is in force, nearly all the operators listed above will force their argument(s) into integer format, and return an integer result. The exceptions,abs
,++
and
, do not change their behavior withuse integer;
Other mathematical operators

Operators such as
**
,sin
andexp
force arguments to floating point format. Bitwise operators
 Arguments are forced into the integer format if not strings.
Bitwise operators during
use integer
 forces arguments to integer format. Also shift operations internally use signed integers rather than the default unsigned.
Operators which expect an integer

force the argument into the integer format. This is applicable
to the third and fourth arguments of
sysread
, for example. Operators which expect a string

force the argument into the string format. For example, this is
applicable to
printf "%s", $value
.
Though forcing an argument into a particular form does not change the stored number, Perl remembers the result of such conversions. In particular, though the first such conversion may be timeconsuming, repeated operations will not need to redo the conversion.
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