Manual Reference Pages - swallow (3)

NAME

swallow(3f) - [M_io] read a file into a character array line by line (LICENSE:PD)

Synopsis
Description
Options
Examples
Author
License

SYNOPSIS

subroutine swallow(filename,pageout)

   character(len=*),intent(in) :: filename
     or
   integer,intent(in)          :: io

   character(len=1),allocatable,intent(out) :: pageout(:)

DESCRIPTION

Read an entire file into memory as a character array, one character variable per line.
NOTE:
Never casually read an entire file into memory if you can process it per line or in smaller units; as large files can consume unreasonable amounts of memory.

OPTIONS

filename
filename to read into memory, or LUN (Fortran Logical Unit Number). If filename is a LUN, file must be opened with
                 form=’unformatted’,access=’stream’
as in
                open(unit=igetunit, file=filename,     &
                & action="read", iomsg=message,        &
                & form="unformatted", access="stream", &
                & status=’old’,iostat=ios)
pageout
array of characters to hold file

EXAMPLES

Sample program

   program demo_swallow
   use M_io,      only : swallow
   implicit none
   character(len=4096)          :: FILENAME   ! file to read
   character(len=:),allocatable :: pageout(:) ! array to hold file in memory
   integer                      :: longest, lines, i
      ! get a filename
      call get_command_argument(1, FILENAME)
      ! allocate character array and copy file into it
      call swallow(FILENAME,pageout)
      if(.not.allocated(pageout))then
         write(*,*)’*demo_swallow* failed to load file ’//FILENAME
      else
         ! write file from last line to first line
         longest=len(pageout)
         lines=size(pageout)
         write(*,*)’number of lines is ’,lines
         write(*,*)’and length of lines is ’,longest
         write(*,’(a)’)repeat(’%’,longest+2)
         write(*,’("%",a,"%")’)(trim(pageout(i)),i=lines,1,-1)
         write(*,’(a)’)repeat(’%’,longest+2)
         deallocate(pageout)  ! release memory
      endif
   end program demo_swallow

Given

first line second line third line

Expected output

    number of lines is 3
    and length of lines is 11

%%%%%%%%%%%%% %third line % %second line% %first line % %%%%%%%%%%%%%

AUTHOR

John S. Urban

LICENSE

Public Domain

swallow (3)

March 11, 2021

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