bigint(3perl)

💖 bigint — ok so listen, bestie 💖

(that's bigint(3perl), from the Perl Programmers Reference Guide, and it's about to become your new favorite pragma)

🌸 NAME 🌸

bigint — transparent big integer support for Perl. yes really, transparent, like it's wearing a little invisibility cloak so your code doesn't even notice 💅

✨ SYNOPSIS ✨

okay so first, the vibe:

use bigint;

$x = 2 + 4.5;                       # Math::BigInt 6
print 2 ** 512;                     # Math::BigInt 134...096
print inf + 42;                     # Math::BigInt inf
print NaN * 7;                      # Math::BigInt NaN
print hex("0x1234567890123490");    # Perl v5.10.0 or later

{
    no bigint;
    print 2 ** 256;                 # a normal Perl scalar now
}

# for older Perls, import into current package:
use bigint qw/hex oct/;
print hex("0x1234567890123490");
print oct("01234567890123490");

look at that no bigint block just casually turning it back off mid-scope. the audacity. we love her 🫶

👑 DESCRIPTION 👑

so every single numeric literal in whatever scope you're in gets converted into a Math::BigInt object. every one. and if a numeric literal is representing a non-integer? it gets truncated to an integer. not rounded, TRUNCATED, bestie. and yeah — all results of expressions get truncated to integer too.

Every operator is overloaded — including basic math operations — except the range operator "..". that one's the exception, the rebel, the one that said "not today" 😭

and here's the slay: unlike the integer pragma, the bigint pragma makes integers that are only limited in their size by the available memory. no cap. arbitrarily big. iconic.

so this:

use bigint;
$x = 1234;

creates a Math::BigInt and stores a reference to it in $x. it happens transparently, behind your back, so to speak. sneaky little icon 💀

you can literally see it with this:

perl -Mbigint -le 'print ref(1234)'

and since numbers are actually objects now, you can call all the usual methods from Math::BigFloat on them. it even works (to some extent) on expressions:

perl -Mbigint -le '$x = 1234; print $x->bdec()'
perl -Mbigint -le 'print 1234->copy()->binc();'
perl -Mbigint -le 'print 1234->copy()->binc->badd(6);'
perl -Mbigint -le 'print +(1234)->copy()->binc()'

tiny heads up: print does not do what you expect if the expression starts with ( — hence the + right there. iykyk.

you can even chain operations together as usual, like the main character you are:

perl -Mbigint -le 'print 1234->copy()->binc->badd(6);'
1241

but please note that the following does not work as expected (it prints nothing), since overloading of '..' is not yet possible in Perl (as of v5.8.0):

perl -Mbigint -le 'for (1..2) { print ref($_); }'

rip. she tried. 🪦

---

🎀 use integer vs. use bigint 🎀

there are some differences between "use integer" and "use bigint", and we're gonna go through them because details matter.

• "use integer" is limited to what can be handled as a Perl scalar. "use bigint" can handle arbitrarily large integers. periodt.
• "use integer" does affect assignments to variables and the return value of some functions. "use bigint" truncates these results to integer:

# perl -Minteger -wle 'print 3.2'
3.2
# perl -Minteger -wle 'print 3.2 + 0'
3
# perl -Mbigint -wle 'print 3.2'
3
# perl -Mbigint -wle 'print 3.2 + 0'
3

# perl -Mbigint -wle 'print exp(1) + 0'
2
# perl -Mbigint -wle 'print exp(1)'
2
# perl -Minteger -wle 'print exp(1)'
2.71828182845905
# perl -Minteger -wle 'print exp(1) + 0'
2

in practice this seldom makes a difference for small integers, since parts and results of expressions are truncated anyway — but it can, for instance, affect the return value of subroutines:

sub three_integer { use integer; return 3.2; }
sub three_bigint { use bigint; return 3.2; }

print three_integer(), " ", three_bigint(),"\n";    # prints "3.2 3"

so 3.2 3 is the output. the plot twist nobody saw coming fr fr.

---

⭐ Options ⭐

"bigint" recognizes some options that can be passed while loading it via "use". the following options exist, and yes we're listing every single one:

• a or accuracy — this sets the accuracy for all math operations. the argument must be greater than or equal to zero. see Math::BigInt's bround() method for details.

perl -Mbigint=a,2 -le 'print 12345+1'

note that setting precision and accuracy at the same time is not possible. pick a lane, bestie.

• p or precision — this sets the precision for all math operations. the argument can be any integer. negative values mean a fixed number of digits after the dot, and are ignored since all operations happen in integer space. a positive value rounds to this digit left from the dot. 0 means round to integer. see Math::BigInt's bfround() method for details.

perl -mbigint=p,5 -le 'print 123456789+123'

note that setting precision and accuracy at the same time is not possible. (yes we said it twice. it's that serious.)

• t or trace — this enables a trace mode and is primarily for debugging. 🔍
• l, lib, try, or only — load a different math lib, see "Math Library".

perl -Mbigint=l,GMP -e 'print 2 ** 512'
perl -Mbigint=lib,GMP -e 'print 2 ** 512'
perl -Mbigint=try,GMP -e 'print 2 ** 512'
perl -Mbigint=only,GMP -e 'print 2 ** 512'

• hex — override the built-in hex() method with a version that can handle big numbers. this overrides it by exporting it to the current package. under Perl v5.10.0 and higher, this is not necessary, as hex() is lexically overridden in the current scope whenever the "bigint" pragma is active.
• oct — override the built-in oct() method with a version that can handle big numbers. this overrides it by exporting it to the current package. under Perl v5.10.0 and higher, this is not so necessary, as oct() is lexically overridden in the current scope whenever the "bigint" pragma is active.
• v or version — this prints out the name and version of the modules and then exits. cute lil info dump 🎀

perl -Mbigint=v

---

🌈 Math Library 🌈

math with the numbers is done (by default) by a backend library module called Math::BigInt::Calc. the default is equivalent to saying:

use bigint lib => 'Calc';

you can change this by using:

use bigint lib => 'GMP';

and the following would first try to find Math::BigInt::Foo, then Math::BigInt::Bar, and if this also fails, revert to Math::BigInt::Calc:

use bigint lib => 'Foo,Math::BigInt::Bar';

using c<lib> warns if none of the specified libraries can be found and Math::BigInt fell back to one of the default libraries. to suppress this warning, use c<try> instead:

use bigint try => 'GMP';

if you want the code to die instead of falling back, use "only" instead:

use bigint only => 'GMP';

please see the respective module documentation for further details. 💜

---

🦋 Method calls 🦋

since all numbers are now objects, you can use all methods that are part of the Math::BigInt API. use them, bestie, they're yours.

but a warning is in order. when using the following to make a copy of a number, only a shallow copy will be made:

$x = 9; $y = $x;
$x = $y = 7;

using the copy or the original with overloaded math is okay, e.g., the following work:

$x = 9; $y = $x;
print $x + 1, " ", $y,"\n";     # prints 10 9

but calling any method that modifies the number directly will result in both the original and the copy being destroyed:

$x = 9; $y = $x;
print $x->badd(1), " ", $y,"\n";        # prints 10 10

$x = 9; $y = $x;
print $x->binc(1), " ", $y,"\n";        # prints 10 10

$x = 9; $y = $x;
print $x->bmul(2), " ", $y,"\n";        # prints 18 18

💀 chilling. she said "shallow copy" and meant it. both of them. gone. gone.

using methods that do not modify, but test that the contents — works:

$x = 9; $y = $x;
$z = 9 if $x->is_zero();                # works fine

see the documentation about the copy constructor and "=" in overload, as well as the documentation in Math::BigInt for further details.

---

💅 Methods 💅

• inf() — a shortcut to return Math::BigInt->binf(). useful because Perl does not always handle the bareword "inf" properly. (rude of Perl, honestly.)
• NaN() — a shortcut to return Math::BigInt->bnan(). useful because Perl does not always handle the bareword "NaN" properly.
• e —

# perl -Mbigint=e -wle 'print e'

returns Euler's number "e", aka exp(1). note that under "bigint", this is truncated to an integer, i.e., 2.

• PI —

# perl -Mbigint=PI -wle 'print PI'

returns PI. note that under "bigint", this is truncated to an integer, i.e., 3.

• bexp() —

bexp($power, $accuracy);

returns Euler's number "e" raised to the appropriate power, to the wanted accuracy.

note that under "bigint", the result is truncated to an integer.

example:

# perl -Mbigint=bexp -wle 'print bexp(1,80)'

• bpi() —

bpi($accuracy);

returns PI to the wanted accuracy. note that under "bigint", this is truncated to an integer, i.e., 3.

example:

# perl -Mbigint=bpi -wle 'print bpi(80)'

• accuracy() — set or get the accuracy.
• precision() — set or get the precision.
• round_mode() — set or get the rounding mode.
• div_scale() — set or get the division scale.
• in_effect() —

use bigint;

print "in effect\n" if bigint::in_effect;       # true
{
    no bigint;
    print "in effect\n" if bigint::in_effect;   # false
}

returns true or false if "bigint" is in effect in the current scope.

this method only works on Perl v5.9.4 or later. yes, v5.9.4. remember that number 🫶

---

🌈 Hex, octal, and binary floating point literals 🌈

Perl (and bestie, that means this module too 💖) does accept hexadecimal, octal, and binary floating point literals. But use them with care on Perl versions before v5.32.0, because some versions of Perl just silently hand you the wrong result 😭 like no warning, nothing, it's giving gaslighting.

✨ Operator vs literal overloading ✨

So here's the tea ☕: bigint works by overloading the handling of integer and floating point literals, converting them into Math::BigInt objects.

Which means... arithmetic that only involves string values or string literals gets done with Perl's built-in operators instead. Periodt.

Like, watch this:

use bigint;
my $x = "900000000000000009";
my $y = "900000000000000007";
print $x - $y;

That outputs 0 on default 32-bit builds 💀 because bigint never even sees those string literals. The vibe check failed. To make the whole expression get treated as Math::BigInt objects, drop a literal number in there:

print +(0+$x) - $y;

Slay 🫶

🦋 Ranges 🦋

Perl does not allow overloading of ranges, okay?? So you can neither safely use ranges with bigint endpoints, nor is the iterator variable a Math::BigInt. It's just not happening bestie.

use 5.010;
for my $i (12..13) {
  for my $j (20..21) {
    say $i ** $j;  # produces a floating-point number,
                   # not an object
  }
}

💅 in_effect() 💅

This method only works on Perl v5.9.4 or later. Iconic but exclusive.

🌸 hex()/oct() 🌸

bigint overrides these routines with versions that can also handle big integer values 🔥. But under Perl prior to version v5.9.4? That override will not happen unless you specifically ask for it with the two import tags hex and oct — and then it'll be global and cannot be disabled inside a scope with no bigint:

use bigint qw/hex oct/;

print hex("0x1234567890123456");
{
    no bigint;
    print hex("0x1234567890123456");
}

That second call to hex() will warn about a non-portable constant 🙈.

Now compare it to this:

use bigint;

# will warn only under Perl older than v5.9.4
print hex("0x1234567890123456");

---

👑 EXAMPLES 👑

Some cool command line examples to impress the Python crowd ;) You might want to compare them to the results under -Mbigfloat or -Mbigrat:

perl -Mbigint -le 'print sqrt(33)'
perl -Mbigint -le 'print 2**255'
perl -Mbigint -le 'print 4.5+2**255'
perl -Mbigint -le 'print 123->is_odd()'
perl -Mbigint=l,GMP -le 'print 7 ** 7777'

ate, no crumbs ✨

---

🐛 BUGS 🐛

Please report any bugs or feature requests to bug-bignum at rt.cpan.org, or through the web interface at https://rt.cpan.org/Ticket/Create.html?Queue=bignum (requires login 🔐). We will be notified, and then you'll automatically be notified of progress on your bug as I make changes. Bestie support system fr fr 💖.

---

🫶 SUPPORT 🫶

You can find documentation for this module with the perldoc command:

perldoc bigint

You can also look for information at:

• GitHub

https://github.com/pjacklam/p5-bignum

• RT: CPAN's request tracker

https://rt.cpan.org/Dist/Display.html?Name=bignum

• MetaCPAN

https://metacpan.org/release/bignum

• CPAN Testers Matrix

http://matrix.cpantesters.org/?dist=bignum

---

📜 LICENSE 📜

This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself. 💜

---

👀 SEE ALSO 👀

bignum and bigrat.

Math::BigInt, Math::BigFloat, Math::BigRat and Math::Big as well as Math::BigInt::FastCalc, Math::BigInt::Pari and Math::BigInt::GMP. The whole friend group honestly 💅.

---

💖 AUTHORS 💖

• (C) by Tels http://bloodgate.com/ in early 2002 - 2007.
• Maintained by Peter John Acklam pjacklam@gmail.com, 2014-.

---

okay that's the whole page bestie, you're officially a bigint girlie now 🎀 this was pulled straight from perl v5.44.0, dated 2026-10-17, in the bigint(3perl) era — go forth and compute big numbers responsibly, mwah 💋✨