Metrologic Optimus R, Руководство по программированию

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184 "C" Programming Guide For Optimus S/R
3.14 File Manipulation
There are many file manipulation routines available for programming the portable
terminals. These routines can help to manipulate the transaction data and ease the
implementation of database system.
Two types of file structures are supported:
Sequential structure called DAT file that is usually used to store transaction data.
Index structure that is usually used to store lookup data. Actually, there are two types of
index file. One is DBF for storing the original data records (data members), and the other
is
IDX
for sorting the records according to the associate key.
These two file structures will be further discussed later in this section.
3.14.1 File System
On each terminal, there is an on-board SRAM for data memory. This is the place where all
the system parameters, program variables, program stack, and file system resides.
3.14.2 Directory
The file system is flat, i.e. it does not support hierarchical tree directory structure, and no
sub-directory can be created. There is a limit for the total number of files, which includes all
DAT files as well DBF files and their associated IDX files.
Max. 255 files for the Optimus S and Optimus R
To get the information of the file directory, you can call filelist() .
3.14.3 File Name
A file name is a null terminated character string containing 1 ~ 8 characters (the null
character not included), which is used to identify the file in the system. There is no file
extension as in MS-DOS operation system.