Dart - Double datatype addition results in long decimal values

Question

In the following program I am adding the list of doubles.

The output I am expecting is 57.7 but it results in 57.699999999999996

void main() {
  List<double> list= [1.0,1.0,1.0,1.0,0.8,52.9];
  double total = 0.0;

  list.forEach((item) {
    total = total + item;
  });
  print(total);

}

Is this a expected behaviour?

Solution 1

Yes, that is expected behavior - to get the desired result use - .toStringAsFixed(1)

void main() {
  List<double> list = [1.0, 1.0, 1.0, 1.0, 0.8, 52.9];
  double total = 0.0;

  list.forEach((item) {
    total = total + item;
  });
  print(total.toStringAsFixed(1));
}

output: 57.7

Solution 2

Using reduce will solve the problem

var total = [1.1, 2.2, 3.3].reduce((a, b) => a + b); // 6.6

Comments

[uaraven]

Welcome to wonderful world of floating point numbers. Yes, that's normal and that question is asked often. See for example stackoverflow.com/questions/29197414/inexact-float-division and all the links in the comments there.