Continue what #4494 started; introduce uid and gid formats.

[perl5.git] / lib / integer.pm

package integer;

=head1 NAME

integer - Perl pragma to compute arithmetic in integer instead of double

=head1 SYNOPSIS

    use integer;
    $x = 10/3;
    # $x is now 3, not 3.33333333333333333

=head1 DESCRIPTION

This tells the compiler to use integer operations
from here to the end of the enclosing BLOCK.  On many machines, 
this doesn't matter a great deal for most computations, but on those 
without floating point hardware, it can make a big difference.

Note that this affects the operations, not the numbers.  If you run this
code

    use integer;
    $x = 1.5;
    $y = $x + 1;
    $z = -1.5;

you'll be left with C<$x == 1.5>, C<$y == 2> and C<$z == -1>.  The $z
case happens because unary C<-> counts as an operation.

Native integer arithmetic (as provided by your C compiler) is used.
This means that Perl's own semantics for arithmetic operations may
not be preserved.  One common source of trouble is the modulus of
negative numbers, which Perl does one way, but your hardware may do
another.

  % perl -le 'print (4 % -3)'
  -2
  % perl -Minteger -le 'print (4 % -3)'
  1

See L<perlmod/Pragmatic Modules>.

=cut

sub import {
    $^H |= 1;
}

sub unimport {
    $^H &= ~1;
}

1;