How to resolve the algorithm Append a record to the end of a text file step by step in the Fortran programming language

Published on 12 May 2024 09:40 PM
#Fortran

How to resolve the algorithm Append a record to the end of a text file step by step in the Fortran programming language

Table of Contents

Problem Statement

Many systems offer the ability to open a file for writing, such that any data written will be appended to the end of the file. Further, the file operations will always adjust the position pointer to guarantee the end of the file, even in a multitasking environment. This feature is most useful in the case of log files, where many jobs may be appending to the log file at the same time, or where care must be taken to avoid concurrently overwriting the same record from another job.

Given a two record sample for a mythical "passwd" file: Resulting file format: should mimic Linux's /etc/passwd file format with particular attention to the "," separator used in the GECOS field. But if the specific language has a particular or unique format of storing records in text file, then this format should be named and demonstrated with an additional example. Expected output: Finally: Provide a summary of the language's "append record" capabilities in a table. eg. Alternatively: If the language's appends can not guarantee its writes will always append, then note this restriction in the table. If possible, provide an actual code example (possibly using file/record locking) to guarantee correct concurrent appends.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Append a record to the end of a text file step by step in the Fortran programming language

Source code in the fortran programming language

      PROGRAM DEMO	!As per the described task, more or less.
      TYPE DETAILS		!Define a component.
       CHARACTER*28 FULLNAME
       CHARACTER*12 OFFICE
       CHARACTER*16 EXTENSION
       CHARACTER*16 HOMEPHONE
       CHARACTER*88 EMAIL
      END TYPE DETAILS
      TYPE USERSTUFF		!Define the desired data aggregate.
       CHARACTER*8 ACCOUNT
       CHARACTER*8 PASSWORD	!Plain text!! Eeek!!!
       INTEGER*2 UID
       INTEGER*2 GID
       TYPE(DETAILS) PERSON
       CHARACTER*18 DIRECTORY
       CHARACTER*12 SHELL
      END TYPE USERSTUFF
      TYPE(USERSTUFF) NOTE	!After all that, I'll have one.
      NAMELIST /STUFF/ NOTE	!Enables free-format I/O, with names.
      INTEGER F,MSG,N
      MSG = 6	!Standard output.
      F = 10	!Suitable for some arbitrary file.
      OPEN(MSG, DELIM = "QUOTE")	!Text variables are to be enquoted.

Create the file and supply its initial content.
      OPEN (F, FILE="Staff.txt",STATUS="REPLACE",ACTION="WRITE",
     1 DELIM="QUOTE",RECL=666)	!Special parameters for the free-format WRITE working.

      WRITE (F,*) USERSTUFF("jsmith","x",1001,1000,
     1 DETAILS("Joe Smith","Room 1007","(234)555-8917",
     2  "(234)555-0077","jsmith@rosettacode.org"),
     2 "/home/jsmith","/bin/bash")

      WRITE (F,*) USERSTUFF("jdoe","x",1002,1000,
     1 DETAILS("Jane Doe","Room 1004","(234)555-8914",
     2  "(234)555-0044","jdoe@rosettacode.org"),
     3 "home/jdoe","/bin/bash")
      CLOSE (F)		!The file is now existing.

Choose the existing file, and append a further record to it.
      OPEN (F, FILE="Staff.txt",STATUS="OLD",ACTION="WRITE",
     1 DELIM="QUOTE",RECL=666,ACCESS="APPEND")

      NOTE = USERSTUFF("xyz","x",1003,1000,		!Create a new record's worth of stuff.
     1 DETAILS("X Yz","Room 1003","(234)555-8193",
     2  "(234)555-033","xyz@rosettacode.org"),
     3 "/home/xyz","/bin/bash")
      WRITE (F,*) NOTE					!Append its content to the file.
      CLOSE (F)

Chase through the file, revealing what had been written..
      OPEN (F, FILE="Staff.txt",STATUS="OLD",ACTION="READ",
     1 DELIM="QUOTE",RECL=666)
      N = 0
   10 READ (F,*,END = 20) NOTE	!As it went out, so it comes in.
      N = N + 1			!Another record read.
      WRITE (MSG,11) N		!Announce.
   11 FORMAT (/,"Record ",I0)	!Thus without quotes around the text part.
      WRITE (MSG,STUFF)		!Reveal.
      GO TO 10			!Try again.

Closedown.
   20 CLOSE (F)
      END

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