KXM@PSUVM.BITNET (Kevin M. Morooney) (01/04/89)
I recently inherited some code which contains the following statements:
DEFINE FILE 20(6, 2,E,J1)
DEFINE FILE 8(9,12,E,J8)
DEFINE FILE 19(9, 8,E,J4)
Correspondingly, there are these kinds of read/writes:
WRITE(20'1, 1001)
READ(19'3, 985)
I can make some guesses as to what is going on but I'd like to be sure.
I'm told the code was running on an Amdahl and I'm trying to get it up
on an IBM. Any insight someone may have would be greatly appreciated.
Kevin Morooney
kxm@psuvm.psu.edujohnl@ima.ima.isc.com (John R. Levine) (01/05/89)
In article <66377KXM@PSUVM> KXM@PSUVM.BITNET (Kevin M. Morooney) writes: >I recently inherited some code which contains the following statements: > DEFINE FILE 20(6, 2,E,J1) > > WRITE(20'1, 1001) I haven't seen a define file since I was programming an 1130 over 20 years ago. The statement made it into IBM 360 Fortran by 1968, the date of the manual I have, and is probably still there. Anyway, here's what your statements mean: 20 - I/O unit number 6 - number of records in the file 2 - record size E - format code, see below J1 - "associated variable" which after each READ, WRITE, or FIND contains the record number of the next record in the file The format codes are E meaning that only formatted reads and writes are allowed and the record size is given in bytes, L meaning that either formatted or unformatted I/O is allowed and the record length is given in bytes, and U meaning that only unformatted I/O is allowed and the record length is given in words. The define file statement is executable even though all of the numbers must be integer constants and must be executed before performing any I/O to the file. In read and write statements, the record number to read or write is written after the I/O unit number separated by an apostrophe. The record number can be an expression. There is also a "find" statement: FIND(unit'recno) which gives the system a hint about the next record number you expect to read. -- John R. Levine, Segue Software, POB 349, Cambridge MA 02238, +1 617 492 3869 { bbn | spdcc | decvax | harvard | yale }!ima!johnl, Levine@YALE.something You're never too old to have a happy childhood.