How to pre-fill a READ statement variable in Fortran? - fortran

Question

I have a program that has a menu with multiple options (search record, add record, delete record, modify record). What I am trying to do is sort of an autofill function.
Ex: A record number is entered into the search option, but after searching through the database, that record is not found. You are then prompted with the option of searching for a different record number or adding a new record with the variable you just entered. If you choose to add, I want the program to call the add subroutine, and already autofill the read statement with the record you read in to you search subroutine.
This what my code looks like (the search subroutine uses a search function to lookup the record number in master.db, and the display subroutine prints out the results on the screen in a formatted array; both the search and display use a master module with the character and integer variables in the record defined):
SUBROUTINE search
IMPLICIT NONE
CHARACTER::readRecord*10, changeOpt*1
INTEGER::recNum, search
OPEN(20, FILE="master.db", FORM="FORMATTED", ACCESS="DIRECT", RECL=100)
DO
CALL SYSTEM ("clear")
WRITE(*,"(2/,20X,A25)")"* * * Search Record * * *"
WRITE(*,100,ADVANCE="NO")"Please enter a record number or Q to exit:"
100 FORMAT(1/,20X,A42,1X)
READ(*,200)readRecord
200 FORMAT(A10)
IF(readSSN=="Q" .OR. readSSN=="q")RETURN
recNum=search(readRecord)
IF (recNum==0)THEN
CALL SYSTEM("clear")
WRITE(*,"(2/,20X,A26)")"* * * Display Record * * *"
WRITE(*,300,ADVANCE="NO")"Record ", readRecord," not found. ","Would you like to add a new record (Y/N)?"
300 FORMAT(1/,20X,A7,A10,A12,1/,20X,A41,1X)
READ*,changeOpt
IF(changeOpt=="Y" .OR. changeOpt=="y") CALL add
CYCLE
ELSE
CALL display
WRITE(*,400,ADVANCE="NO")"Press ENTER to continue:"
400 FORMAT(1/,20X,A24,1X)
READ*,
END IF
END DO
CLOSE(20)
END SUBROUTINE search
In the add subroutine, everything up to
recNum=search(readRecord)
is identical to the search subroutine. What I want is a way to take the information entered to
READ(*,200)readRecord
in the search subroutine, somehow temporarily save it, and then once the add subroutine is called, automatically enter it into the
READ(*,200)readRecord
in the add subroutine, so that the user doesn't have to re-enter the record number they want to add.
A way I think this might be accomplished, but I don't know the syntax for would be:
! WRITE readRecord to some specific place in master.mod
! CALL add
! Once in add:
! At READ(*,200)readRecord, search police.mod to check if it
! has a readRecord already written in it.
! If it does, autofill READ(*,200)readRecord with the readRecord
! from police.mod.
! Then delete readRecord from police.mod (so that if you go directly
! into the add subroutine later, it doesn't autofill a record from a
! previous search).
! If there is no readRecord in police.mod then just prompt for user
! to enter readRecord like in the search subroutine.
Any suggestions would be greatly appreciated.

Answer 1

You do not say that clearly, but I assume that by "autofill the READ variable" you want that the string is pre-filled on the screen in the prompt and the user can edit it or just hit Enter.
That is not possible in Fortran with the readstatement. The statement does not work this way and has no such option.
You can achieve similar things with certain libraries. They are usually written in C. You won't be able to use the read statement in them though and they are usually written in C. For example the readline and ncurses libraries. See related
pre-fill stdin in C
What you can do in standard Fortran is to have an if condition and check if the user decided to enter an empty string and use some default previous value if that happened.