& regmatch()
 
  Syntax: regmatch(<string>,<regexp>[,<register list>])
 
  This function matches the regular expression <regexp> against the 
  entirety of <string>, returning 1 if it matches and 0 if it does 
  not.
 
  If <register list> is specified, there is a side-effect: any 
  parenthesized substrings within the regular expression will be set 
  into the specified local registers, in the order they were specified 
  in the list. <register list> can be a list of one through nine 
  numbers. If the specified register is -1, the substring is not 
  copied into a register.
 
  For example: 
  if <string> is 'cookies=30', and <regexp> is '(.+)=([0-9]*)' 
  (parsed; note that escaping may be necessary), then the 0th 
  substring matched is 'cookies=30', the 1st substring is 'cookies', 
  and the 2nd substring is '30'. If <register list> is '0 3 5', then 
  %q0 will become "cookies=30", %q3 will become "cookies", and %q5 
  will become "30". If <register list> was '0 -1 5', then the 
  "cookies" substring would simply be discarded.

  See Also: REGEXPS