String Length in Swift in Swift

We can get the length of a string using the .count property like this:

var message = "Hello world"

// Printing the length:
print(message.count) // Output: 11

// Changing the message:
message += "!"

// Printing the new length:
print(message.count) // Output: 12

Accessing characters from the end:

The length is useful for accessing characters from the end of a string.

Because strings are 0-indexed, the index of the last character is length - 1:

var message = "Hello world"
let length = message.count

// Printing the last character:
let lastIdx = message.index(message.endIndex, offsetBy: -1)
print(message[lastIdx]) // Output: d

// Printing the second to last character:
let secondLastIdx = message.index(message.endIndex, offsetBy: -2)
print(message[secondLastIdx]) // Output: l

In general, if you want the nth last character, you use message[message.index(message.endIndex, offsetBy: -n)].

Slicing characters from the end:

The length is also useful for slicing some characters from the end of a string:

var message = "Hello world"
let length = message.count

// Slicing last 4 characters:
var lastChars = String(message.suffix(4))
print(lastChars) // Output: orld

// Slicing last 7 characters:
lastChars = String(message.suffix(7))
print(lastChars) // Output: o world

In general, if you want the last n characters, you use String(message.suffix(n)).

Assignment
Follow the Coding Tutorial and let's practice with string length!

Hint
Look at the examples above if you get stuck.