RUBY

ruby replace words in a string

# Replace first value a return new string
sentence = 'pop poper'
sentence.sub('pop', 'stop')
=> 'stop poper'
puts sentence
=> 'pop poper'

# Replace all matches and return new string
sentence = 'pop poper'
sentence.gsub('pop', 'stop')
=> 'stop stoper'
puts sentence
=> 'pop poper'

# Replace first value and update existing string
sentence = 'pop poper'
sentence.sub!('pop', 'stop')
=> 'stop poper'
puts sentence
=> 'stop poper'

# Replace all matches and update string
sentence = 'pop poper'
sentence.gsub!('pop', 'stop')
=> 'stop stoper'
puts sentence
=> 'stop stoper'

substring replace in ruby

user_input = "mooventhan" 
user_input.gsub!(/moo/, "hel")
print user_input

replace strring by another string ruby

myString = "Welcome to JavaScript!"

myString["JavaScript"]= "Ruby"

puts myString
=> "Welcome to Ruby!"