change string ruby code example

Example 1: ruby replace certain character

# Ruby language
str_old = "first-name last-name"
str_old.sub("-", "_") 		# Replace first "-" with "_"
str_old.gsub("-", "_") 		# Replace all "-" with "_"

Example 2: replace strring by another string ruby

myString = "Welcome to JavaScript!"

myString["JavaScript"]= "Ruby"

puts myString
=> "Welcome to Ruby!"