[ruby] Does Ruby have a string.startswith("abc") built in method?

Does Ruby have a some_string.starts_with("abc") method that's built in?

Your question title and your question body are different. Ruby does not have a starts_with? method. Rails, which is a Ruby framework, however, does, as sepp2k states. See his comment on his answer for the link to the documentation for it.

You could always use a regular expression though:

if SomeString.match(/^abc/) 
   # SomeString starts with abc

^ means "start of string" in regular expressions

If this is for a non-Rails project, I'd use String#index:

"foobar".index("foo") == 0  # => true

You can use String =~ Regex. It returns position of full regex match in string.

irb> ("abc" =~ %r"abc") == 0
=> true
irb> ("aabc" =~ %r"abc") == 0
=> false