notabs(3f) - [fpm_strings:NONALPHA] expand tab characters (LICENSE:PD)
subroutine notabs(INSTR,OUTSTR,ILEN)
character(len=*),intent=(in) :: INSTR
character(len=*),intent=(out) :: OUTSTR
integer,intent=(out) :: ILEN
NOTABS() converts tabs in INSTR to spaces in OUTSTR while maintaining columns. It assumes a tab is set every 8 characters. Trailing spaces are removed.
In addition, trailing carriage returns and line feeds are removed (they are usually a problem created by going to and from MSWindows).
What are some reasons for removing tab characters from an input line? Some Fortran compilers have problems with tabs, as tabs are not part of the Fortran character set. Some editors and printers will have problems with tabs. It is often useful to expand tabs in input files to simplify further processing such as tokenizing an input line.
instr Input line to remove tabs from
outstr Output string with tabs expanded. Assumed to be of sufficient
length
ilen Significant length of returned string
Sample program:
program demo_notabs
! test filter to remove tabs and trailing white space from input
! on files up to 1024 characters wide
use fpm_strings, only : notabs
character(len=1024) :: in,out
integer :: ios,iout
do
read(*,'(A)',iostat=ios)in
if(ios /= 0) exit
call notabs(in,out,iout)
write(*,'(a)')out(:iout)
enddo
end program demo_notabs
GNU/Unix commands expand(1) and unexpand(1)
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| character(len=*), | intent(in) | :: | instr | |||
| character(len=*), | intent(out) | :: | outstr | |||
| integer, | intent(out) | :: | ilen |
elemental impure subroutine notabs(instr,outstr,ilen) ! ident_31="@(#)fpm_strings::notabs(3f): convert tabs to spaces while maintaining columns, remove CRLF chars" character(len=*),intent(in) :: instr ! input line to scan for tab characters character(len=*),intent(out) :: outstr ! tab-expanded version of INSTR produced integer,intent(out) :: ilen ! column position of last character put into output string ! that is, ILEN holds the position of the last non-blank character in OUTSTR integer,parameter :: tabsize=8 ! assume a tab stop is set every 8th column integer :: ipos ! position in OUTSTR to put next character of INSTR integer :: lenin ! length of input string trimmed of trailing spaces integer :: lenout ! number of characters output string can hold integer :: istep ! counter that advances thru input string INSTR one character at a time character(len=1) :: c ! character in input line being processed integer :: iade ! ADE (ASCII Decimal Equivalent) of character being tested ipos=1 ! where to put next character in output string OUTSTR lenin=len_trim(instr( 1:len(instr) )) ! length of INSTR trimmed of trailing spaces lenout=len(outstr) ! number of characters output string OUTSTR can hold outstr=" " ! this SHOULD blank-fill string, a buggy machine required a loop to set all characters SCAN_LINE: do istep=1,lenin ! look through input string one character at a time c=instr(istep:istep) ! get next character iade=ichar(c) ! get ADE of the character EXPAND_TABS : select case (iade) ! take different actions depending on which character was found case(9) ! test if character is a tab and move pointer out to appropriate column ipos = ipos + (tabsize - (mod(ipos-1,tabsize))) case(10,13) ! convert carriage-return and new-line to space ,typically to handle DOS-format files ipos=ipos+1 case default ! c is anything else other than a tab,newline,or return insert it in output string if(ipos > lenout)then write(stderr,*)"*notabs* output string overflow" exit else outstr(ipos:ipos)=c ipos=ipos+1 endif end select EXPAND_TABS enddo SCAN_LINE ipos=min(ipos,lenout) ! tabs or newline or return characters or last character might have gone too far ilen=len_trim(outstr(:ipos)) ! trim trailing spaces end subroutine notabs