Double Methods - Dart Programming

double exposes useful methods to round a value to a nearby integer (.floor(), .ceil(), .round()), keep a value inside a range with .clamp(), and format fixed-decimal text with .toStringAsFixed(). Each rounding method returns an int; clamp keeps a double receiver as double; toStringAsFixed returns a String.

Program

Play the program to round 3.7 three different ways, clamp it into a range, and format it with two fixed decimals.

double_methods.dart

void main() {
  double value = 3.7;
  var down = value.floor();
  var up = value.ceil();
  var near = value.round();
  var bounded = value.clamp(0.0, 3.0);
  var fixed = value.toStringAsFixed(2);
  print('$down $up $near $bounded $fixed');
}

floor and ceil `.floor()` rounds toward negative infinity; `.ceil()` rounds toward positive infinity. Both return `int`.

round `.round()` rounds halfway cases away from zero and returns an `int`. `3.7.round()` is `4`.

clamp `.clamp(lo, hi)` keeps a value inside a range. With a `double` receiver, the result is a `double`; here `3.7` is capped to `3.0`.

toStringAsFixed `.toStringAsFixed(n)` formats a `double` with exactly `n` digits after the decimal point and returns a `String`.