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Strings

Updated Aug 24, 2023 ·

Overview​

Strings are used to store and display text in Ruby.

  • Strings can be joined together
  • Strings can include variables
  • Can use single ' ' or double " " quotes

Example using string joining:

first_name = "James"
last_name = "Smith"
puts first_name + " " + last_name

Output:

James Smith

Single Quotes vs Double Quotes​

Single quotes keep the text exactly as typed, while double quotes allow Ruby to interpret special characters like new lines (\n) and tabs (\t).

# Double quotes interpret escape characters
puts "Hello\nWorld"

# Single quotes treat characters literally
puts 'Hello\nWorld'

Output:

Hello
World
Hello\nWorld

String Interpolation​

We can use string interpolation to place variables inside a string:

first_name = "James"
last_name = "Smith"
puts "My first name is #{first_name} and my last name is #{last_name}"

Output:

My first name is James and my last name is Smith

String interpolation only works with double quotes. Using single quotes prints the text as is:

first_name = "James"
last_name = "Smith"
puts 'My first name is #{first_name} and my last name is #{last_name}'

Output:

My first name is #{first_name} and my last name is #{last_name}

Multi-line Strings​

For large blocks of text, we can use the here document (heredoc) syntax. This allows multi-line strings while preserving spaces, tabs, and line breaks.

poem = <<POEM
    What a beautiful language Ruby is
    It allows multi-line strings
    Even preserves indentation and spacing
    Shakespeare
POEM

puts poem

Output:

    What a beautiful language Ruby is
    It allows multi-line strings
    Even preserves indentation and spacing
    Shakespeare

Heredoc is ideal for storing paragraphs, poems, or formatted text in a string. Everything between the start and end identifiers is included exactly as typed.

Comparing Strings​

You can test whether strings are equal or different, and you can also compare them based on their alphabetical order.

  • == checks if two strings are exactly the same
  • != checks if two strings are not the same
  • Alphabetical comparison uses < and >
  • Comparison is case-sensitive

Example:

a = "Hello"
b = "hello"
c = "Hello"

puts a == b
puts a == c
puts a != b

Output:

false
true
true

Alphabetical Comparison​

For alphabetical comparisons, Ruby compares strings character by character.

  • < checks if a string comes before another alphabetically
  • > checks if a string comes after another alphabetically
  • Comparisons are case-sensitive; uppercase letters come before lowercase

Example:

puts "A" < "B"
puts "a" < "z"
puts "M" > "F"

Output:

true
true
true

Sorting Words​

Each letter is treated individually, so for example, "Hello" comes before "Help" because L comes before P.

Example:

puts "Hello" < "Help"

Output:

true

String Concatenation​

String concatenation in means joining one string with another to form a single piece of text. There are various ways to concatenate strings.

Using the Plus Operator​

The + operator combines strings into a new one, while keeping the original strings unchanged, which helps preserve original data.

Example:

first_name = "James"
last_name = "Smith"

full_name = first_name + " " + last_name
puts full_name
puts first_name

Output:

James Smith
James

Reassigning with Plus-Equals​

The += operator joins strings and updates the original variable, which is a quick way to overwrite values.

first_name = "James"
last_name = "Smith"

first_name += " " + last_name
puts first_name

Output:

James Smith

Using the Concat Method​

The concat method changes the original string in place, so the variable now holds the new combined value.

Example:

first_name = "James"
last_name = "Smith"

first_name.concat(" ").concat(last_name)
puts first_name

Output:

James Smith

Using the Prepend Method​

The prepend method modifies the original string by adding new content before it, which permanently changes its value.

name = "Smith"
name.prepend("James ")
puts name

Output:

James Smith

Using the Shovel Operator​

The shovel operator (<<) is a symbolic alternative to concat. It appends text directly to the original string and is useful when building strings step by step.

title = "Engineer "
title << "Senior "
title << "Level"
puts title

Output:

Engineer Senior Level