compareTo method Null safety

int compareTo (
  1. num other

Compares this to other.

Returns a negative number if this is less than other, zero if they are equal, and a positive number if this is greater than other.

The ordering represented by this method is a total ordering of num values. All distinct doubles are non-equal, as are all distinct integers, but integers are equal to doubles if they have the same numerical value.

For doubles, the compareTo operation is different from the partial ordering given by operator==, operator< and operator>. For example, IEEE doubles impose that 0.0 == -0.0 and all comparison operations on NaN return false.

This function imposes a complete ordering for doubles. When using compareTo the following properties hold:

  • All NaN values are considered equal, and greater than any numeric value.
  • -0.0 is less than 0.0 (and the integer 0), but greater than any non-zero negative value.
  • Negative infinity is less than all other values and positive infinity is greater than all non-NaN values.
  • All other values are compared using their numeric value.


print(1.compareTo(2)); // => -1
print(2.compareTo(1)); // => 1
print(1.compareTo(1)); // => 0

// The following comparisons yield different results than the
// corresponding comparison operators.
print((-0.0).compareTo(0.0));  // => -1
print(double.nan.compareTo(double.nan));  // => 0
print(double.infinity.compareTo(double.nan)); // => -1

// -0.0, and NaN comparison operators have rules imposed by the IEEE
// standard.
print(-0.0 == 0.0); // => true
print(double.nan == double.nan);  // => false
print(double.infinity < double.nan);  // => false
print(double.nan < double.infinity);  // => false
print(double.nan == double.infinity);  // => false


int compareTo(num other);