Floats Functions

Nette\Utils\Floats is a static class with useful functions for comparing float numbers.

Installation:

composer require nette/utils

All examples assume the following class alias is defined:

use Nette\Utils\Floats;

Motivation

Wondering what a float comparison class is for? You can use operators <, >, ===, you think. This is not entirely true. What do you think will print this code?

$a = 0.1 + 0.2;
$b = 0.3;
echo $a === $b ? 'same' : 'not same';

If you run the code, some of you will be surprised that the program printed not same.

Mathematical operations with float numbers cause errors due to conversion between decimal and binary systems. For example 0.1 + 0.2 equates to 0.300000000000000044…. Therefore, when comparing floats, we must tolerate a small difference from a certain decimal place.

And that's what the Floats class is doing. The following comparison will work as expected:

echo Floats::areEqual($a, $b) ? 'same' : 'not same'; // same

When trying to compare NAN, it throws an \LogicException exception.

The Floats class tolerates differences less than 1e-10. If you need to work with more precision, use the BCMath library instead.

Float Comparison

areEqual (float $a, float $b): bool

Returns true if $a = $b.

Floats::areEqual(10, 10.0); // true

isLessThan (float $a, float $b): bool

Returns true if $a < $b.

Floats::isLessThan(9.5, 10.2); // true
Floats::isLessThan(INF, 10.2); // false

isLessThanOrEqualTo (float $a, float $b): bool

Returns true if $a <= $b.

Floats::isLessThanOrEqualTo(9.5, 10.2);    // true
Floats::isLessThanOrEqualTo(10.25, 10.25); // true

isGreaterThan (float $a, float $b): bool

Returns true if $a > $b.

Floats::isGreaterThan(9.5, -10.2); // true
Floats::isGreaterThan(9.5, 10.2);  // false

isGreaterThanOrEqualTo (float $a, float $b): bool

Returns true if $a >= $b.

Floats::isGreaterThanOrEqualTo(9.5, 10.2);  // false
Floats::isGreaterThanOrEqualTo(10.2, 10.2); // true

compare (float $a, float $b): int

If $a < $b, it returns -1, if they are equal it returns 0 and if $a > $b it returns 1.

It can be used, for example, with the usort function.

$arr = [1, 5, 2, -3.5];
usort($arr, [Float::class, 'compare']);
// $arr is [-3.5, 1, 2, 5]

Helpers Functions

isZero (float $value): bool

Returns true if value is zero.

Floats::isZero(0.0); // true
Floats::isZero(0);   // true

isInteger (float $value): bool

Returns true if value is integer.

Floats::isInteger(0);    // true
Floats::isInteger(0.0);  // true
Floats::isInteger(-5.0); // true

Floats::isInteger(-5.1); // false
Floats::isInteger(INF);  // false
Floats::isInteger(NAN);  // false