Strings in Ruby - Learning Ruby 2

Ruby has great string support. This post summarises the functions that are available.

This is not designed to be a tutorial for others, but rather a record for myself in learning Ruby.

.downcase

This method turns any characters in a string to lowercase.

a = "My String".downcase 

returns

"my string"

.upcase

.upcase method does the opposite of downcase. It will change the case of any lowercase characters to uppercase.

"My String".upcase

returns

"MY STRING"

.gsub

.gsub is a way of substituting text in one string for a different string.

"Hello".gsub("ell", "orr")

returns

"Horro"

String Interpolation

This is potentially the most useful way of working with strings when outputting them.

first_name = "Foo"
surname = "Bar"
puts "Hello #{first_name} #{surname}

String Methods

There are a whole host of methods for strings. You can see them all with:

"".methods

This will display all the methods that are available for a string. One of the most important ones is .chomp.

Firstly, we will get a string with the command gets - this stands for get string.

puts "What is your name?" 
gets = name

Once you run this you will get a string with the name that you enter and a \n on the end - the newline character. This can be annoying, but .chomp will remove this:

gets = name.chomp

This means that the string has the newline character removed.

.count

If you wish to count the amount of times a set of characters appear in a string, use the .count method.

"banana".count("a")

will return the number 3.

"banana".count("ba") 

will return 4.

String Operations

"ban" + "ana" 

will return banana.

You cannot do the same thing with -.

Converting Strings to Integers

Sometimes you will have a string such as '1', but want to add this to an integer variable 2. If you try this:

a = '1'
b = 2 
p a + b 

you will find that you will have a problem as the string does not add easily to the integer. You will see the error:

TypeError (no implicit conversion of Integer into String)

To get around this, you need to cast the a variable to an intger:

a = '1'
a.to_i

or to do this more succinctly:

a = '1'.to_i

The .to_i converts the variable to an integer and the addition will work.