Manual Reference Pages - read_all (3)
NAME
read_all(3f) - [M_io] read a line from specified LUN into allocatable string up to line length limit (LICENSE:PD)
CONTENTS
Syntax
Description
Options
Returns
Example
Author
License
SYNTAX
function read_all(line,lun) result(ier)
character(len=:),allocatable,intent(out) :: line integer,intent(in),optional :: lun integer,intent(out) :: ier
DESCRIPTION
Read a line of any length up to programming environment’s maximum line length. Requires Fortran 2003+.
It is primarily expected to be used when reading input which will then be parsed.
The input file must have a PAD attribute of YES for the function to work properly, which is typically true.
The simple use of a loop that repeatedly re-allocates a character variable in addition to reading the input file one buffer at a time could (depending on the programming environment used) be inefficient, as it could reallocate and allocate memory used for the output string with each buffer read.
OPTIONS
LINE line read LUN optional LUN (Fortran logical I/O unit) number. Defaults to stdin.
RETURNS
IER zero unless an error occurred. If not zero, LINE returns the I/O error message.
EXAMPLE
Sample program:
program demo_read_all use,intrinsic :: iso_fortran_env, only : stdin=>input_unit implicit none open(unit=stdin,pad=’yes’) ichars=0 msg=’’ do read(stdin,advance=’no’,size=isize,iostat=ios,fmt=’(*(a),t1)’,iomsg=msg)a if(ios.ne.0) exit ichars=ichars+1 write(*,*)ichars,a enddo write(*,*)’END’,ichars,isize,trim(msg)end program testit use M_io, only : read_all implicit none character(len=:),allocatable :: line INFINITE: do while (read_all(line)==0) write(*,’(a)’)’[’//line//’]’ enddo INFINITE end program demo_read_all
AUTHOR
John S. Urban
LICENSE
Public Domain
| read_all (3) | October 17, 2020 |
