31.11. use integeruse integer; $x = 10/3; # $x is now 3, not 3.33333333333333333 This lexically scoped pragma tells the compiler to use integer operations from here through the end of the enclosing block. On many machines, this doesn't matter a great deal for most computations, but on those few remaining architectures without floatingpoint hardware, it can amount to a dramatic performance difference. Note that this pragma affects certain numeric operations, not the numbers themselves. For example, if you run this code: you'll be left with $x == 1.8, $y == 2 and $z == 1. The $z case happens because unary  counts as an operation, so the value 1.8 is truncated to 1 before its sign bit is flipped. Likewise, functions that expect floatingpoint numbers, such as sqrt or the trig functions, still receive and return floats even under use integer. So sqrt(1.44) is 1.2, but 0 + sqrt(1.44) is now just 1.use integer; $x = 1.8; $y = $x + 1; $z = 1.8; Native integer arithmetic as provided by your C compiler is used. This means that Perl's own semantics for arithmetic operations might not be preserved. One common source of trouble is the modulus of negative numbers. Perl may do it one way, but your hardware may do it another: % perl le 'print (4 % 3)' 2 % perl Minteger le 'print (4 % 3)' 1 Copyright © 2002 O'Reilly & Associates. All rights reserved. 
