Manual Reference Pages - find_field (3m_strings)

NAME

find_field(3f) - [M_strings:TOKENS] parse a string into tokens (LICENSE:MIT)

Synopsis
Description
Options
Examples
Author
License
Version

SYNOPSIS

subroutine find_field (string, field, position, delims, delim, found)

    character*(*),intent(in)           :: string
    character*(*),intent(out)          :: field
    integer,optional,intent(inout)     :: position
    character*(*),optional,intent(in)  :: delims
    character*(*),optional,intent(out) :: delim
    logical,optional,intent(out)       :: found

DESCRIPTION

Find a delimited field in a string.
Here is my equivalent, which I have used for nearly 2 decades, as you can see from the date. This does not try to mimic the C strtok (and does not have its limitations either). It is in a much more native Fortran style.
It is a little more complicated than some because it does some things that I regularly find useful. For example, it can tell the caller what trailing delimiter it found. This can be useful, for example, to distinguish between
       somefield, someotherfield
versus
       somefield=somevalue, someotherfield
Also, I have a bit of special handling for blanks. All the usage information is in the argument descriptions. Note that most of the arguments are optional.
from comp.lang.fortran @ Richard Maine

OPTIONS

STRING The string input.

FIELD The returned field. Blank if no field found.

POSITION
On entry, the starting position for searching for the field. Default is 1 if the argument is not present. On exit, the starting position of the next field or len(string)+1 if there is no following field.

DELIMS String containing the characters to be accepted as delimiters. If this includes a blank character, then leading blanks are removed from the returned field and the end delimiter may optionally be preceded by blanks. If this argument is not present, the default delimiter set is a blank.

DELIM Returns the actual delimiter that terminated the field. Returns char(0) if the field was terminated by the end of the string or if no field was found. If blank is in delimiters and the field was terminated by one or more blanks, followed by a non-blank delimiter, the non-blank delimiter is returned.

FOUND True if a field was found.

EXAMPLES

Sample of uses

       program demo_find_field
       use M_strings, only : find_field
       implicit none
       character(len=256)           :: string
       character(len=256)           :: field
       integer                      :: position
       character(len=:),allocatable :: delims
       character(len=1)             :: delim
       logical                      :: found

       delims=’[,]’
       position=1
       found=.true.
       string=’[a,b,[ccc,ddd],and more]’
       write(*,’(a)’)trim(string)
       do
          call find_field(string,field,position,delims,delim,found=found)
          if(.not.found)exit
          write(*,’("<",a,">")’)trim(field)
       enddo
       write(*,’(*(g0))’)repeat(’=’,70)

       position=1
       found=.true.
       write(*,’(a)’)trim(string)
       do
          call find_field(string,field,position,’[], ’,delim,found=found)
          if(.not.found)exit
          write(*,’("<",a,">",i0,1x,a)’)trim(field),position,delim
       enddo
       write(*,’(*(g0))’)repeat(’=’,70)

       end program demo_find_field

Results:

    > [a,b,[ccc,ddd],and more]
    > <>
    > <a>
    > <b>
    > <>
    > <ccc>
    > <ddd>
    > <>
    > <and more>
    > <>
    > ==================================================================
    > [a,b,[ccc,ddd],and more]
    > <>2 [
    > <a>4 ,
    > <b>6 ,
    > <>7 [
    > <ccc>11 ,
    > <ddd>15 ]
    > <>16 ,
    > <and>20
    > <more>257 ]
    > ==================================================================

AUTHOR

Richard Maine

LICENSE

MIT

VERSION

version 0.1.0, copyright Nov 15 1990, Richard Maine
Minor editing to conform to inclusion in the string procedure module

Nemo Release 3.1

find_field (3m_strings)

January 10, 2025

Generated by manServer 1.08 from 3e3fa14f-52d8-4b8f-b435-c6e3888ebb51 using man macros.

STRING	The string input.
FIELD	The returned field. Blank if no field found.
POSITION
	On entry, the starting position for searching for the field. Default is 1 if the argument is not present. On exit, the starting position of the next field or len(string)+1 if there is no following field.
DELIMS	String containing the characters to be accepted as delimiters. If this includes a blank character, then leading blanks are removed from the returned field and the end delimiter may optionally be preceded by blanks. If this argument is not present, the default delimiter set is a blank.
DELIM	Returns the actual delimiter that terminated the field. Returns char(0) if the field was terminated by the end of the string or if no field was found. If blank is in delimiters and the field was terminated by one or more blanks, followed by a non-blank delimiter, the non-blank delimiter is returned.
FOUND	True if a field was found.