What is the "=~" operator in Ruby?

I saw this on a screencast and couldn't figure out what it was. Reference sheets just pile it in with other operators as a general pattern match operator.

Solution 1:

It matches string to a regular expression.

'hello' =~ /^h/ # => 0

If there is no match, it will return nil. If you pass it invalid arguments (ie, left or right-hand sides are not correct), it will either throw a TypeError or return false.

Solution 2:

From ruby-doc :

str =~ obj => fixnum or nil

Match—If obj is a Regexp, use it as a pattern to match against str, and returns the offset position the match starts, or nil if there is no match. Otherwise, invokes obj.=~, passing str as an argument. The default =~ in Object returns false.

"cat o' 9 tails" =~ /\d/   #=> 7
"cat o' 9 tails" =~ 9      #=> false