Полезная информация

Programming Perl

Programming PerlSearch this book
Previous: 7.2.42 Math::BigFloat - Arbitrary-Length, Floating-Point Math PackageChapter 7
The Standard Perl Library
Next: 7.2.44 Math::Complex - Complex Numbers Package
 

7.2.43 Math::BigInt - Arbitrary-Length Integer Math Package

use Math::BigInt;

$i = Math::BigInt->new($string);

# BINT is a big integer string; in all following cases $i remains unchanged.
# All methods except bcmp() return a big integer string, or strings.
$i->bneg;       # return negative of $i
$i->babs        # return absolute value of $i
$i->bcmp(BINT)  # compare $i to BINT; see below for return value
$i->badd(BINT)  # return sum of BINT and $i
$i->bsub(BINT)  # return $i minus BINT
$i->bmul(BINT)  # return $i multiplied by BINT
$i->bdiv(BINT)  # return $i divided by BINT; see below for return value
$i->bmod(BINT)  # return $i modulus BINT
$i->bgcd(BINT)  # return greatest common divisor of $i and BINT
$i->bnorm       # return normalization of $i

This module allows you to use integers of arbitrary length. Integer strings (BINTs) have the form /^\s*[+-]?[\d\s]+$/. Embedded whitespace is ignored. Output values are always in the canonical form: /^[+-]\d+$/ . For example:

'+0'                # canonical zero value
'   -123 123 123'   # canonical value:  '-123123123'
'1 23 456 7890'     # canonical value:  '+1234567890'

The return value NaN results when an input argument is not a number, or when a divide by zero is attempted. The bcmp() method returns -1, 0, or 1 depending on whether $f is less than, equal to, or greater than the number string given as an argument. If the number string is undefined or null, the undefined value is returned. In a list context the bdiv() method returns a two-element array containing the quotient of the division and the remainder; in a scalar context only the quotient is returned.

When you use this module, Perl's basic math operations are overloaded with routines from Math::BigInt. Therefore, you don't have to employ the methods shown above to multiply, divide, and so on. You can rely instead on the usual operators. Given this code:

$a = Math::BigInt->new("42 000 000 000 000");
$b = Math::BigInt->new("-111111");

the following five lines yield these string values for $c:

$c = 42000000000000 - -111111;
                          # 42000000111111; ordinary math--$c is a double
$c = $a - $b;             # "+42000000111111"; $c is now a BigInt object
$c = $a - -111111;        # "+42000000111111"; $c is now a BigInt object
$c = $a->bsub($b);        # "+42000000111111"; $c is just a string
$c = $a->bsub(-111111);   # "+42000000111111"; $c is just a string


Previous: 7.2.42 Math::BigFloat - Arbitrary-Length, Floating-Point Math PackageProgramming PerlNext: 7.2.44 Math::Complex - Complex Numbers Package
7.2.42 Math::BigFloat - Arbitrary-Length, Floating-Point Math PackageBook Index7.2.44 Math::Complex - Complex Numbers Package