Arithmetic Operators in Swift: + - * / and %

TL ; DR:

• We can tell computers to perform calculations for us using +, -, *, /:

  print(2 + 6) // Prints 8
  print(10 - 7) // Prints 3
  print(3 * 3) // Prints 9
  print(6 / 2) // Prints 3
  

  
  
  

• We can also use variables. In these examples, Swift will replace variable num with its value 6 to do the calculations:

  let num = 6
  print(num + 5) // Prints 11
  print(10 - num) // Prints 4
  print(3 * num) // Prints 18
  print(num / 2) // Prints 3
  

  
  

Full lesson:

Computers absolutely excel at performing calculations. The "compute" in their name comes from their historical association with providing answers to mathematical questions.

These calculations can be performed either directly with numbers or with variables that are assigned numeric values.

Arithmetic operators are used with numeric values to perform common mathematical operations:

Note that performing arithmetic on variables does not change the variable - you can only update a variable using the = sign.

Let's go through some examples together to better understand how each operator works:

Addition

// Declare 2 integer variables and initialize them:
let a = 2
let b = 3

print(a + b) // Output: 5

print(a + 10) // Output: 12

Subtraction

// Declare 2 integer variables and initialize them:
let a = 2
let b = 3

print(a - b) // Output: -1

print(10 - b) // Output: 7

Multiplication

// Declare 2 integer variables and initialize them:
let a = 2
let b = 3

print(a * 5) // Output: 10

print(2 * a * b) // Output: 12

Division

In Swift, division between integers returns only the integral part of the result:

// Declare 2 integer variables and initialize them:
let a = 2
let b = 3

print(20 / 3) // Output: 6

print(b / a) // Output: 1

If we want to get the real result of the division, the values have to be of type Double (a plain number like 2 in Double(7) / 2 is read as a Double automatically):

// Declare 2 integer variables and initialize them:
let a = 2
let b = 3

print(Double(7) / 2) // Output: 3.5

print(Double(b) / Double(a)) // Output: 1.5

Assignment
Follow the Coding Tutorial and let's practice with arithmetic operators!

Hint
Look at the examples above if you get stuck.