BigInt Arithmetic - Dart Programming

BigInt is Dart's arbitrary-precision integer. Build values with BigInt.parse(text) for decimal text or BigInt.from(int) to widen an ordinary int. The usual operators +, -, *, ~/ stay exact on BigInt operands no matter how large, so they handle magnitudes the 64-bit int cannot represent. BigInt.toString() is the full decimal expansion.

Program

Play the program to parse a 21-digit BigInt, double it, integer-divide it, and count its decimal digits.

bigint.dart

void main() {
  var big = BigInt.parse('100000000000000000000');
  var two = BigInt.from(2);
  var doubled = big * two;
  var halved = big ~/ two;
  var digits = big.toString().length;
  print('$doubled $halved digits=$digits');
}

BigInt.parse `BigInt.parse(decimal)` reads arbitrary-precision integers from text. There is no overflow on the parsed value.

BigInt.from `BigInt.from(int)` widens an ordinary `int` to a `BigInt` so it can mix with other `BigInt` operands.

exact arithmetic `+`, `*`, `~/` on `BigInt` operands stay exact regardless of magnitude; the result is another `BigInt`.