Expand All

Strings

Goals

  • Understand when to use strings

  • Learn how to combine strings

  • Learn about string interpolation

Step 1

Type this in irb, hitting Enter after each line:

IRB
'a string in single quotes'
"a string in double quotes"

A string is a series of characters. Strings can be created using either single or double quotes.

These strings weren't saved into a variable. What happens to data not saved into a variable?

What happens if you start a string with one kind of quote and end with another? How can you fix it?

Step 2

Type this in irb, hitting Enter after each line:

IRB
'Hello, ' + 'Jane'
'apples' * 3

Strings can be added to each other or multipled by numbers. What does this do?

Step 3

Type this in irb, hitting Enter after each line:

IRB
name = 'Jane'
"Hello #{name}"

(the {} characters are generally called curly braces)

This is called string interpolation. String interpolation lets you embed a Ruby statement in another string. It only works with double quotes: what happens when you try the same thing with single quotes?

Type this in irb, hitting Enter after each line:

IRB
"Two plus two is #{2 + 2}"

The code in the curly braces can be any valid Ruby statement. Try putting various things in the curly brackets to see what works and what doesn't.

Concatenation vs. Interpolation

first = "Joe"
last = "Smith"

+ does concatenation

full = first + " " + last

#{} does interpolation

full = "#{first} #{last}"

Step 4

Try out some of these String methods.

Type this in irb, hitting Enter after each line:

IRB
'I have many characters'.length
'forwards'.reverse
'jane smith'.upcase
'a plain old sentence'.delete('aeiou')

Recall that you can see what methods are available for an object by calling .methods on it.

Type this in irb, hitting Enter after each line:

IRB
'some string'.methods

Explanation

Strings are a key way to present information in your programs. Since a human will probably be reading the output of your program eventually, and humans speak words rather than numbers, you will often want to use strings.

A not at all complete summary of methods on String:

length how long is this string (characters)
reverse return same string, reversed
upcase return same string, IN UPPER CASE
delete([another string]) delete all characters in the second string from the first
methods get the names of all methods you can perform on string

Further Reading

Ruby's documentation for String

Next Step:

Go on to Input And Output

Back to Datatypes