# Operators for Calculation#

Operators let you do various things with variables.

## Typical Mathematical Operators#

We have used these already in all of the examples without formally introducing them, but here are the common mathematical operators you already know:

`+`

and`-`

add/subtract two things`*`

and`/`

multiply/divide two things`%`

is one you may remember from primary school. This is the remainder of a division.`7 % 3`

would result in`1`

. This operator comes up whenever you need to do alternating stripes or need to work out stuff surrounding date and time manually. The operator itself is called the "modulo" operator.

## Assignment#

As mentioned earlier, `=`

is not actually the mathematical equals sign, but an assignment operator.

## Short Forms#

When dealing with numbers, there are a lot of specialized operators that you might come across:

- Adding something to a variable would usually be
`totalCalories = totalCalories + intake`

, but it can also be written as`totalCalories += intake`

. - Subtracting something would be
`creditsInWallet = creditsInWallet - itemPrice`

or can be abbreviated as`creditsInWallet -= itemPrice`

. - These also exist for multiplication, where
`width = width * scaleFactor`

becomes`width *= scaleFactor`

. - I don't have a great example for division, but I bet you already know how this works by now.

## VERY Short Forms for Increment/Decrement#

We'll be doing a LOT of counting variables up and down. And this is quite common in programming in general, that's why pretty much all languages have even shorter versions for incrementing or decrementing a variable. Let's say we have an integer variable called `counter`

. We can then write any of these:

`counter++`

(post-increment) will return its current value and then add one to that current value`counter--`

(post-decrement) will return its current value and then subtract one from that current value`++counter`

(pre-increment) adds one to the current value of the variable and then return the new value`--counter`

(pre-decrement) subtracts one from the current value of the variable and then return the new value

These are especially useful in loops.

## Further Details#

There are even more operators in Java, and they also come with additional rules, like their precedence. If you're interested in this topic, Please take a look at the Java Tutorials page about Operators

## Relevant excerpt from Learning Processing#

(the section starts at 1:48:56 and runs through 1:53:20, the video should start and stop on these automatically.)