C Library Functions - rd (3)

NAME

rd(3f) - [M_io:READ] ask for string from standard input with user-definable prompt (LICENSE:PD)

  function rd(prompt,default) result(out)

   character(len=*),intent(in)              :: prompt

  One of

   character(len=*),intent(in)              :: default
   character(len=:),allocatable,intent(out) :: out

   integer,intent(in)                       :: default
   integer,intent(out)                      :: out

   real,intent(in)                          :: default
   real,intent(out)                         :: out

   doubleprecision,intent(in)               :: default
   doubleprecision,intent(out)              :: out

   logical,intent(in)                       :: default
   logical,intent(out)                      :: out

Description
Options
Returns
Examples
Author
License

DESCRIPTION

Ask for string or value from standard input with user-definable prompt up to 20 times.
Do not use the function in an I/O statement as not all versions of Fortran support this form of recursion. Numeric values may be input in standard INTEGER, REAL, and DOUBLEPRECISION formats or as whole numbers in base 2 to 36 in the format BASE#VALUE.

OPTIONS

prompt Prompt string; displayed on same line as input is read from

default
default answer on carriage-return. The type of the default determines the type of the output.

RETURNS

out returned string or value. If an end-of-file or system error is encountered the string "EOF" is returned, or a "Nan" REAL numeric value, or huge(0), or .false. .

EXAMPLES

Sample program:

   program demo_rd
   use M_io, only : rd
   implicit none
   character(len=:),allocatable :: mystring
   doubleprecision              :: d
   real                         :: r
   integer                      :: i
   logical                      :: l

   INFINITE: do
      mystring=rd(’Enter string or "STOP":’,default=’Today’)
      if(mystring == ’STOP’)stop
      i=rd(’Enter integer:’,default=huge(0))
      r=rd(’Enter real:’,default=huge(0.0))
      d=rd(’Enter double:’,default=huge(0.0d0))
      l=rd(’Enter logical:’,default=.false.)

      write(*,*)’I=’, i, ’R=’, r, ’D=’,d,  ’MYSTRING=’, mystring
      write(*,*)’L=’, l
   enddo INFINITE

   end program demo_rd

AUTHOR

John S. Urban, 1993

LICENSE

Public Domain

Nemo Release 3.1

rd (3)

February 23, 2025

Generated by manServer 1.08 from d838a3f2-e9f7-46bc-9f5c-a0f12fc94fc4 using man macros.

prompt	Prompt string; displayed on same line as input is read from
default
	default answer on carriage-return. The type of the default determines the type of the output.