Physical Files and Logical Files
Physical files contain the actual data that is stored on an IBM® i, and a description of how data is to be presented to or received from a program. They contain only one record format, and one or more members.
A physical file can have a keyed sequence access path. This means that data is presented to an ILE C/C++ program in a sequence that is based on one or more key fields in the file.
Logical files do not contain data. They contain a description of records that are found in one or more physical files. A logical file is a view or representation of one or more physical files. Logical files that contain more than one format are referred to as multi-format logical files.
If your program processes a logical file which contains more than
one record format, you can use the _Rformat()
function
to set the format you wish to use.
Some operations cannot be performed on logical files. If you open
a logical file for stream file processing with open modes w
, w+
, wb
,
or wb+
, the file is opened but not cleared. If you open
a logical file for record file processing with open modes wr or wr+,
the file is opened but not cleared.