3️⃣Operators

Fall 2023 | Vin Bui

We have seen the four basic math operations in elementary school: addition, subtraction, multiplication, and division. In Swift, we can use operators to perform these operations.

Basic Operators

var a = 0
a = a + 10
a = a - 5
a = a * a
a = a / 10

The following lines are equivalent:

These operators are self-explanatory; however, if we were to take a closer look at the the line a = a / 10 we can notice that the output is 2 instead of 2.5. The reason for this is because the type of a is an Int. If we were to perform these operations on a, then we must also use an Int.

Then, how do we get the value 2.5? Because the type of a is an Int, then we must introduce a new variable of type Double or Float since we cannot change the type of a variable once initialized. We would also need to make sure that the values in which we apply these operators on must also be a Double or Float.

Let's take a look at the line Double(a). This is known as type casting. Because a is an Int and we needed a Double, Double(a) converts the value 2 to 2.0. Note that this does not change the type of a. It only produces a value to be used for that operation.

One more common operator we may see is the modulus operator (%). This is similar to the / operator except we return the remainder.

Common Operators

The following is a list of common operators that we are likely to use.

>	greater than	||	or
>=	greater than or equal to	&&	and
<	less than	!	not
<=	less than or equal to
==	equal to
!=	not equal to

String Interpolation

String interpolation is a way of combining variables and constants inside a string. Take a look at this example:

var name = "Vin"
"My name is \(name)."

Of course, we could have used the + operator to concatenate these strings together.

The problem with this approach is efficiency especially if we want to concatenate multiple variables. Another issue with using + is that Swift does not allow types such as Int or Float to be glued with a String.

We could cast age to a String but that would be expensive.

Using string interpolation is a lot more efficient and looks cleaner too!