String Length in Kotlin

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

var message = "Hello world"

// Printing the length:
println(message.length) // Output: 11

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

// Printing the new length:
println(message.length) // 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:

val message = "Hello world"
val length = message.length

// Printing the last character:
println(message[length - 1]) // Output: d

// Printing the second to last character:
println(message[length - 2]) // Output: l

In general, if you want the nth last character, you use message[length - n].

Slicing characters from the end:

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

val message = "Hello world"
val length = message.length

// Slicing last 4 characters:
var lastChars = message.substring(length - 4)
println(lastChars) // Output: orld

// Slicing last 7 characters:
lastChars = message.substring(length - 7)
println(lastChars) // Output: o world

In general, if you want the last n characters, you use message.substring(length - n).

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

Hint
Look at the examples above if you get stuck.