Built in Operators » Histórico » Revisión 3
Revisión 2 (Federico Vera, 2018-07-08 05:57) → Revisión 3/6 (Federico Vera, 2018-07-08 05:58)
# Built in Operators
There are three basic sets of operators available:
## Arithmetic
All of the arithmetic operators are included and available: `+`, `-`, `*`, `/`
and of course `%` (modulo).
## Boolean
Boolean operators will consider `false` every value equal to zero ([`0 ± 0.000000000001`](https://redmine.riddler.com.ar/projects/exp4j/repository/revisions/master/entry/src/main/java/net/objecthunter/exp4j/operator/Operator.java#L70)), and `true` every other value.
But they are warrantied to return `1.0` for `true` and `0.0` for `false`. The
available operators are: `&` (and), `|` (or), `¬` (not).
There are also a set of [[Extra Functions|Extra Functions and Operators]]
## Precedence
For those who don't know, precedence of operators refers to which of the
operators will be evaluated first when left alone. I won't bother you with
numbers, the order of evaluation is as follows:
```
FIRST-> * / % - + ¬ & | == != <-LAST
----- --- - - - -----
^^^ The dashes indicate groups with the same precedence
```
When operators have the same precedence they will be evaluated from left to
right.
***Note:*** as in primary school (and beyond) you can always alter the
precedence of operators with the use of parentheses.
## Factorial
Factorial isn't technically an operator... it's a function but since it's so common, it's implemented by using the `!` symbol and with more precedence than the arithmetic multiplication. Even though the implementation of operators is trivial in `exp4j` the factorial is the only postfix unary operator, so it deserves a [special case](https://redmine.riddler.com.ar/projects/exp4j/repository/revisions/master/entry/src/main/java/net/objecthunter/exp4j/operator/Operator2.java#L183).
**Note:** Factorials from `0!` to `21!` are guaranteed to be correct, bigger than `21!` may suffer lost of precision because of `double` rounding.
**Note 2:** Factorials bigger than `170!` will rise an `IllegalArgumentException` since the value will be `Double.INFINITY`.
## Code
The code for the operators is [here](https://redmine.riddler.com.ar/projects/exp4j/repository/revisions/master/entry/src/main/java/net/objecthunter/exp4j/operator/Operators.java).
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