Strings

String interpolation

name = "World"
puts "Hello #{name}"
puts "The total is #{1+1}"
# "the total is 2"

String interpolation allows you to combine strings together

Extract substring

string = "abc123"
string[0,3]
# "abc"
string[3,3]
# "123"
string[0..-2]
# "abc12"
#remove or replace the substring
string[0..2] = ""
puts string
# "123"

A substring is a small part of a string, which is useful if you only want that specific part, like the beginning, middle, or end

Convert a string to lowercase or uppercase

"HELLO World".downcase  # "hello world"
"hello worlD".upcase    # "HELLO WORLD"
"hEllo wOrlD".capitalize # "Hello world"
"hEllo WOrlD".swapcase  # "HeLLO woRLd"

useful methods

Function Name	Output	Note
length or size	"HELLO World".length => 11 "HELLO World".size => 11	Returns the length of the string
reverse	"hello worlD".reverse => "Dlrow olleh"	Returns the reversed string
include? other_str	"hEllo wOrlD".include? "w" => true	Returns true if the string or character exists, otherwise returns false
gsub(pattern, replacement)	"hEllo wOrlD".gsub(" ", "_") => "hEllo_wOrlD"	gsub or global substitute replaces one or more strings with the provided string
gsub(pattern, hash)	"organization".gsub("z", 'z' => 's') => "organisation"	gsub or global substitute replaces one or more strings with the provided hash
gsub(pattern)	"Price of the phone is 1000 AUD".gsub(/\d+/) {\| s\| '$'+s } "Price of the phone is $1000 AUD"	gsub or global substitute replaces one or more strings with the provided block
strip	" hEllo WOrlD ".strip "hEllo WOrlD"	It will remove (trim) any leading and trailing characters: null (“\x00”), horizontal tab (“\t”), newline (\n), vertical tab (“\v”), form feed (f), carriage return(\r), space (" ")
prepend	a = "world" <br> a.prepend("hello ") "hello world"	Adds the string before another string
insert	a = "hello" <br> a.insert(a.length, " world") "hello world"	Inserts the string at a specific position
start_with?	string = "ruby programming" string.start_with? "ruby" true	Checks if the string starts with a specific prefix
end_with?	string = "ruby programming" string.end_with? "ruby" false	Checks if the string ends with a specific prefix
delete_suffix	string = "sausage is expensive" string.delete_suffix(" is expensive") "sausage"	Deletes the suffix from the string
delete_prefix	string = "sausage is expensive" string.delete_prefix("sausage") " is expensive"	Deletes the prefix from the string
split	string = "a b c d" <br> string.split ["a", "b", "c", "d"]	Converts the string into an array of characters
join	arr = ['a', 'b', 'c'] <br> arr.join => "abc"	Converts an array into a string
to_i	a = "49" <br> a.to_i => 49	Converts the string into an integer
chop	"abcd?".chop("?") => "abcd"	Deletes the last character from the string
count	str = "aaab" <br> str.count("a") 3	Counts the characters in the string
to_f	a = "49" a.to_f 49.0	Converts the string into a floating point number
to_sym	a = "key" a.to_sym :key	Converts the string into a symbol
match	"abcd?".match(/ab/) => #<MatchData "ab">	Converts the pattern into a regular expression and calls its match method on the string
empty?	"hello".empty? => false	Returns true if the length of the string is zero
squeeze	"Booook".squeeze => "Bok"	Returns a copy of the string where runs of the same character are replaced by a single character
*	puts "Ruby " * 4 => Ruby Ruby Ruby Ruby	Returns the concatenation of multiple copies of self
+	"sammy " + "shark" => "sammyshark"	Returns the concatenation of self and the given other string
eql?	s = 'foo' => true s.eql?('foo') => true	Returns true if the objects have the same length and content; false otherwise

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