C Library Functions - regcomp (3)

NAME

regcomp(3f) - [M_regex] Compile a regular expression into a regex object

Synopsis
Description
Options
Examples
See Also

SYNOPSIS

subroutine regcomp(this,pattern,flags,status)

     type(regex_type), intent(out)          :: this
     character(len=*), intent(in)           :: pattern
     character(len=*), intent(in), optional :: flags
     integer, intent(out), optional         :: nmatch
     integer, intent(out), optional         :: status

DESCRIPTION

The regcomp() function compiles an RE written as a string into an internal form for use by regexec().

OPTIONS

THIS new regex object

PATTERN
regex pattern string

FLAGS flag characters:

x= extended regex (REG_EXTENDED). Default is obsolete ("basic") REs.

m= multi-line (REG_NEWLINE). Compile for newline-sensitive matching. By default, newline is a completely ordinary character with no special meaning in either REs or strings. With this flag, ’[^’ bracket expressions and . never match newline, a ’^’ anchor matches the null string after any newline in the string in addition to its normal function, and the ’$’ anchor matches the null string before any newline in the string in addition to its normal function.

i= case-insensitive (REG_ICASE)

n= no MATCH required (REG_NOSUB) Compile for matching that need only report success or failure, not what was matched.

NMATCH number of subexpressions in regular expression

STATUS If absent, errors are fatal

EXAMPLES

Sample program

   program demo_regcomp
   use M_regex, only: regex_type, regcomp, regexec, regfree
   use M_regex, only: regmatch
   implicit none
   type(regex_type)             :: regex
   integer                      :: matches(2,1)
   character(len=:),allocatable :: input_line
   character(len=:),allocatable :: output_line
   character(len=:),allocatable :: expression
   logical                      :: match
   integer                      :: ipass
   integer                      :: istart
      expression= "[-0-9.*/+]+"                              ! define extended regular expression
      input_line= "30*0 250*1 5 AND 6 7:and some text8 999"  ! define an input line to search for the expression
      call regcomp(regex,expression,’x’)                     ! compile the regex
      ipass=1                                                ! initialize pass counter
      INFINITE: do                     ! find match, then look again in remainder of line till all matches found
         match=regexec(regex,input_line,matches)        ! look for a match in (remaining) string
         if(.not.match)exit INFINITE                    ! if no match found exit
         output_line=regmatch(1,input_line,matches)     ! use bounds in MATCHES to select the matching substring
         write(*,’(8x,*(a))’) ’match="’,output_line,’"’ ! show match
         istart=matches(2,1)+1                          ! find beginning of remainder of string
         if(istart.gt.len(input_line))exit INFINITE     ! reached end of string
         input_line=input_line(istart:)                 ! reduce string by any previous match
         ipass=ipass+1                                  ! increment count of passes made
      enddo INFINITE                                    ! free memory used for compiled regular expression
      call regfree(regex)
   end program demo_regcomp

Expected output

   match="30*0"
   match="250*1"
   match="5"
   match="6"
   match="7"
   match="8"
   match="999"

C Library Functions - regcomp (3)

NAME

CONTENTS

SYNOPSIS

DESCRIPTION

OPTIONS

EXAMPLES

SEE ALSO