# 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.

## 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
``````