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Manual Reference Pages  - len_white (3m_strings)

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NAME

len_white(3f) - [M_strings:LENGTH] get length of string trimmed of whitespace. (LICENSE:PD)

CONTENTS

Synopsis
Description
Options
Returns
Examples
Notes
Author
License

SYNOPSIS

elemental integer function len_white(string)

    character(len=*) :: string

DESCRIPTION

len_white(3f) returns the position of the last character in string that is not a whitespace character. The Fortran90 intrinsic LEN_TRIM(3) should be used when trailing whitespace can be assumed to always be spaces.

This procedure was heavily used in the past because ANSI FORTRAN 77 character objects are fixed length and blank padded and the LEN_TRIM(3) intrinsic did not exist. It should now be used only when whitespace characters other than blanks are likely.

OPTIONS

string	input string whose trimmed length is being calculated ignoring all trailing whitespace characters.

RETURNS

len_white
	the number of characters in the trimmed string

EXAMPLES

Sample Program:

   program demo_len_white

     use M_strings, only : len_white
     implicit none
     character(len=80) :: s
     integer           :: lgth, lastnb
     intrinsic len

     s=’ ABCDEFG abcdefg ’
     lgth = len(s)
     lastnb = len_white(s)

     write(*,*) ’total length of variable is ’,lgth
     write(*,*) ’trimmed length of variable is ’,lastnb
     write(*,*) ’trimmed string=[’,s(:lastnb),’]’

    end program demo_len_white

Results:

    total length of variable is           80
    trimmed length of variable is           16
    trimmed string=[ ABCDEFG abcdefg]

NOTES

o	len_white

     is a resource-intensive routine. Once the end of
     the string is found, it is probably best to keep track of it in
     order to avoid repeated calls to len_white. Because they
     might be more efficient, consider looking for vendor-supplied or
     system-optimized equivalents. For example:

        o lnblnk - Solaris f77
        o len_trim - FORTRAN 90

o	Some compilers seem to have trouble passing a string of variable length properly. To be safe, use something like this:

      subroutine message(s)
       character(len=*) :: s ! s is of variable length
          lgth=len(s)        ! get total length of variable
          ! explicitly specify a substring instead of just variable name
          lastnb = len_white(s(:lgth))
          write(*,*)’error:[’,s(:lastnb),’]’
      end subroutine messages

AUTHOR

John S. Urban

LICENSE

Public Domain

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Nemo Release 3.1

len_white (3m_strings)

January 10, 2025

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