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C Library Functions  - regmatch (3)

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NAME

regmatch(3f) - [M_regex] return selected substring defined by the MATCHES(2,:) array

CONTENTS

Synopsis
Description
Options
Returns
Examples

SYNOPSIS

function regmatch(match,string,matches)

   character(len=matches(2,match)-matches(1,match)+1) :: regmatch
   integer, intent(in)                                :: match, matches(2,*)
   character(len=*), intent(in)                       :: string

DESCRIPTION

A convenience function to return a specific substring from the input STRING, defined by the MATCHES() array.

OPTIONS

match	the count into the start and end matrix matches(:,MATCH)
string	the string to find the substrings in
matches
	the start and end matrix generated from calling REGEXEC(3f).

RETURNS

regmatch
	the selected substring extracted from STRING.

EXAMPLES

Sample program:

   program demo_regmatch
   ! read regular expression from command line and look for it in lines read from stdin.
   use M_regex, only: regex_type, regcomp, regexec, regmatch, regfree
   implicit none
   integer                      :: command_argument_length
   character(len=:),allocatable :: command_argument
   character(len=1024)          :: input_line
   type(regex_type)             :: regex
   logical                      :: match
   integer,parameter            :: max_subexpressions=10
   integer                      :: matches(2,max_subexpressions)
   integer                      :: ios
      !find length of command argument
      call get_command_argument(number=1,length=command_argument_length)
      ! allocate a string long enough to hold the argument
      allocate(character(len=command_argument_length) :: command_argument)
      ! get the command argument
      call get_command_argument(1, command_argument)

      ! compile up regular expression
      call regcomp(regex,command_argument,’x’)

      ! read lines and look for match to expression
      INFINITE: do
         read(*,’(a)’,iostat=ios)input_line
         if(ios.ne.0)exit INFINITE
         ! look for a match in (remaining) string
         match=regexec(regex,input_line,matches)
         ! if no match found go for next line
         if(.not.match)cycle INFINITE
         ! show line with match
         write(*,’(a)’) trim(input_line)
      enddo INFINITE

      ! free memory used for compiled regular expression
      call regfree(regex)

   end program demo_regmatch

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Nemo Release 3.1

regmatch (3)

February 23, 2025

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