Records and Files

A record is a sequence of values or a sequence of characters. There are three kinds of Fortran records, as follows:

• Formatted

  A record containing formatted data that requires translation from internal to external form. Formatted I/O statements have explicit format specifiers (which can specify list-directed formatting) or namelist specifiers (for namelist formatting). Only formatted I/O statements can read formatted data.

• Unformatted

  A record containing unformatted data that is not translated from internal form. An unformatted record can also contain no data. The internal representation of unformatted data is processor- dependent. Only unformatted I/O statements can read unformatted data.

• Endfile

  The last record of a file. An endfile record can be explicitly written to a sequential file by an ENDFILE statement.

A file is a sequence of records. There are two types of Fortran files, as follows:

• External

  A file that exists in a medium (such as computer disks or terminals) external to the executable program.

  Records in an external file must be either all formatted or all unformatted. There are two ways to access records in external files: sequential and direct access.

  In sequential access, records are processed in the order in which they appear in the file. In direct access, records are selected by record number, so they can be processed in any order.

• Internal

  Memory (internal storage) that behaves like a file. This type of file provides a way to transfer and convert data in memory from one format to another. The contents of these files are stored as scalar character variables.