Basic Operators and Operands - Images: Japanese

In programming, when we talk about the result of a calculation like addition, we use the phrase "returns a value."

In everyday math, you'd say "the answer to 1 + 1 is 2," right?

In programming, you'd phrase that as "the expression 1 + 1 returns 2."

It's a small difference in wording, but you'll hear it a lot in textbooks and on the job, so it's worth getting familiar with.

If it ever trips you up, just map it back to simple arithmetic and it'll click.

In Swift, the + symbol can also be used for string concatenation — not just addition. Just place + between two strings and you're good to go.

print("初音ミク" + "が好きです。") // The two strings get joined together, outputting '初音ミクが好きです。'.

String concatenation comes up constantly in programming, so make sure this one sticks.

Swift provides operators like += and -= that perform addition or subtraction while also assigning the result back at the same time. You'll find the same thing in other languages too. Here are some examples:

var n = 1
n += 1 // Adds 1 to variable 'n' and assigns the result back to it
print(n) // Outputs 2

var n1 = 1
n1 -= 1 // Subtracts 1 from variable 'n1' and assigns the result back to it
print(n1) // Outputs 0

var n2 = 1
n2 *= 3 // Multiplies variable 'n2' by 3 and assigns the result back to it
print(n2) // Outputs 3

var n3 = 10
n3 /= 2 // Divides variable 'n3' by 2 and assigns the result back to it
print(n3) // Outputs 5

var n4 = 7
n4 %= 5 // Applies remainder division to variable 'n4' by 5 and assigns the result back to it
print(n4) // Outputs 2

Of these, '+=' and '-=' are the ones you'll use most often, so make sure you know them well.

Also, in Swift, += is used to add elements to an array, so keep that in the back of your mind too.

※ For more on arrays, check out this article.

In programming, you'll often hear the terms increment and decrement.

These refer to adding 1 to or subtracting 1 from a target operand, and they're built into almost every language.

Here's what they look like. The example below is JavaScript:

var n = 1;

++n; // Adds 1
--n; // Subtracts 1

If you've worked with other languages, this notation should look familiar.

Here's the thing though — in Swift, increment and decrement operators have been deprecated, so don't use them.

As of the current mainstream version of Swift (2016), they still work, but they're being dropped entirely starting around Swift 3.

So in Swift, to increment or decrement, just write it out plainly like this:

var n = 0

n = n + 1 // increment

print(n) // Outputs 1

n = n - 1 // decrement

print(n) // Outputs 0

Having used increment and decrement so much in other languages, it's easy to reach for them out of habit — so watch yourself there.