BigInteger Usage Overview

Big Integers

Creating Big Integers

To create a big integer you can parse a string:

BigInteger.parse("-1122334455667788990011223344556677889900", 10)

Or use the extensions or companion function for Long, Int, Byte or Short

val bigIntegerExtension = 234L.toBigInteger()
val bigIntegerCompanion = BigInteger.fromLong(234L)

Or use extensions functions for String

"12345678".toBigInteger()

Basic Arithmetic Operations

Addition

val a = BigInteger.fromLong(Long.MAX_VALUE)
val b = BigInteger.fromInt(Integer.MAX_VALUE)

val sum = a + b
println("Sum: $sum")
----- Output -----
Sum: Sum: 9223372039002259454

Subtraction

val a = BigInteger.fromLong(Long.MIN_VALUE)
val b = BigInteger.fromLong(Long.MAX_VALUE)

val difference = a - b
println("Difference: $difference")
----- Output -----
Difference: -18446744073709551615

Multiplication

val a = BigInteger.fromLong(Long.MAX_VALUE)
val b = BigInteger.fromLong(Long.MIN_VALUE)

val product = a * b

println("Product: $product")
----- Output -----
Product: -85070591730234615856620279821087277056

Division - Quotient

val a = BigInteger.fromLong(Long.MAX_VALUE)
val b = BigInteger.fromInt(Int.MAX_VALUE)

val dividend = a + b
val divisor = BigInteger.fromLong(Long.MAX_VALUE)

val quotient = dividend / divisor
        println("Quotient: $quotient")
----- Output -----
Quotient: 1

Division - Remainder

val a = BigInteger.fromLong(Long.MAX_VALUE)
val b = BigInteger.fromInt(Int.MAX_VALUE)

val dividend = a + b
val divisor = BigInteger.fromLong(Long.MAX_VALUE)

val remainder = dividend % divisor
println("Remainder: $remainder")
----- Output -----
Remainder: 2147483647

Division - Quotient and Remainder

val a = BigInteger.fromLong(Long.MAX_VALUE)
val b = BigInteger.fromInt(Int.MAX_VALUE)

val dividend = a + b
val divisor = BigInteger.fromLong(Long.MAX_VALUE)

val quotientAndRemainder = dividend divrem divisor

println("Quotient: ${quotientAndRemainder.quotient} \nRemainder: ${quotientAndRemainder.remainder}")
----- Output -----
Quotient: 1 
Remainder: 2147483647

Bitwise Operations

Shift Left

val a = BigInteger.fromByte(1)

val shifted = a shl 215
println("Shifted: $shifted")
----- Output -----
Shifted: 52656145834278593348959013841835216159447547700274555627155488768

Shift Right

val a = BigInteger.parseString("100000000000000000000000000000000", 10)

val shifted = a shr 90
----- Output -----
Shifted: 80779

Xor

val operand = BigInteger.parseString("11110000", 2)
val mask = BigInteger.parseString("00111100", 2)

val xorResult = operand xor mask

println("Xor result: ${xorResult.toString(2)}")
----- Output -----
Xor result: 11001100

And

val operand = BigInteger.parseString("FFFFFFFFFF000000000000", 16)
val mask =    BigInteger.parseString("00000000FFFF0000000000", 16)
val andResult = operand and mask
println("And result: ${andResult.toString(16)}")
----- Output -----
And result: ff000000000000

Or

val operand = BigInteger.parseString("FFFFFFFFFF000000000000", 16)
val mask =    BigInteger.parseString("00000000FFFF0000000000", 16)
val orResult = operand or mask
println("Or result: ${orResult.toString(16)}")
----- Output -----
Or result: ffffffffffff0000000000

Inverted "precise"

Unlike Java BigInteger which does two's complement inversion, this method does bitwise inversion,

i.e.: If the number was "1100" binary, invPrecise returns "0011" => "11" => 4 in base 10

In the same case Java BigInteger would return "1011" => -13 two's complement base 10

val operand = BigInteger.parseString("11110000", 2)
val invResult = operand.invPrecise()
println("Inv result: ${invResult.toString(2)}")
----- Output -----
Inv result: 1111

Modular integers

A modInverse function that is equivalent to java BigInteger modInverse is available. Note that this method will produce a BigInteger not a ModularBigInteger

Big integers can be converted to modularIntegers with same modulo, and then inverse() method is available. This method will return ModularBigInteger

val a = 100_002.toBigInteger()
val modularA = a.toModularBigInteger(500.toBigInteger())
println("ModularBigInteger: ${modularA.toStringWithModulo()}")
----- Output -----
ModularBigInteger: 2 mod 500

If you want to create more ModularBigIntegers with the same module, you can retrieve creator by calling getCreator

More inforamtion about the ModularBigIntegers can be found in the ModularBigInteger wiki page