Stream input/output in Fortran

Abstract

Traditionally, and indeed until the advent of Fortran2003, Standard Fortran I/O has been entirely record-based. This is fine if you are reading or writing a file of records such as a text file, where each line is a record, since it means that you don't need to be concerned about the record terminators (which, depending on the platform, may be line-feeds, or carriage-returns, or both). It can, however, be a serious handicap when you want to use Fortran to read a file generated by some instrument, or produced by a package such as a spreadsheet or database system. Often these files do not have records that Fortran can recognise, or they have a more complex structure than a simple linear sequence of records, but Standard Fortran has not previously provided any means of accessing them simply as a stream of bytes or characters. Another problem is that sometimes one wants to access the records in some random order, rather than in a strict sequence. One can do this in Fortran using direct-access files, but these are restricted to files where all records have the same length. Stream I/O provides solutions to all these problems.