GET

Syntax

GET [#channel\file_position,] [var1 *[,vari]* …] or

GET [#channel,] [var1 *[,vari]* …]

Location Toolkit II, THOR XVI

This command, together with PUT, helps to provide the QL with a means of using a file as a store for variables. The QL stores variables in one of four ways: short%(range -128 to 127) is stored as 2 bytes. Short integers are only available on Minerva ROMs, when integer tokenisation is enabled. integer%(range -32768 to 32767) is stored as 4 bytes. float(eg. 1.23 or any numbers outside the integer% range) is stored as 6 bytes. string$(eg. ‘Hello’) is stored as 2 bytes containing the length of the string followed by the string itself.

GET enables variables which have been stored in this manner to be retrieved from a file opened to the given channel (default #3). The variable stored at the current position in the file (or the file position given with the command, if the first variant is used) is read directly into the variable name given with the command.

If you provide more than one variable name as the second, third parameter etc, then more variables will be read from the file in one go.

If the first variant is used, the file position is always calculated as an absolute distance from the start of the file. However, to help you, if you supply a variable for the file_position (eg. GET \pointer), this variable will always be updated to the current file pointer at the end of the command.

Compare GET \pointer+3 which supplies an expression for the file_pointer and cannot therefore be updated automatically by the command.

If no variable is specified, the file pointer will be set to the specified position if the first variant is used.

If the second variant is used, this will have no effect.

Example

A program to store three names on a file and then to retrieve them (this would be useful in a database for instance):

100 RESTORE
110 DIM a$(3,20)
120 FOR i=1 TO 3: READ a$(i)
130 OPEN_NEW #3,ram1_storage
140 PUT #3,a$(1),a$(2),a$(3)
150 CLOSE #3 160 :
170 REPeat opt_loop
180   CLS: INPUT 'Which Number Name do you want?',no$
190   IF no$='':NEXT opt_loop
200   IF no$(1) INSTR '123': opt=no$(1): EXIT opt_loop
210 END REPeat opt_loop
220 OPEN_IN#3, ram1_storage
230 FOR i=1 TO opt:GET#3,retrieve$
240 PRINT retrieve$
250 CLOSE #3
260 DATA 'Fred Bloggs','Filthy Rich','Peter Rabbit'

NOTE 1

The example works fine if only a few fields have to be stored. Generally, it is better to move around a file using file pointers in a file based database.

NOTE 2

Current versions of the Turbo and Supercharge compilers are not able to compile programs which use GET.

NOTE 3

Except under SMS v2.81+, this command can crash the system if you try to GET a string variable which has been dimensioned {or even set with LOCal a$(512) for example}. This can be avoided by using:

a$=FILL$(' ',512)

to initialise the string instead.

NOTE 4

Although it is possible to use this command with non-file related channels, this is inadvisable, as each entry would need to be typed in from the keyboard in its internal form, which can be rather difficult. If you do use the command on a non-file related channel by accident, press the Break key to escape.

CROSS-REFERENCE

See PUT, BPUT, BGET, LGET, WGET.