Reference Guide > G Routines > GET_LUN Procedure
  

GET_LUN Procedure
Allocates a file unit from a pool of free units.
Usage
GET_LUN, unit
Input Parameters
unit—A named variable.
Output Parameters
unit—On output, unit is converted into an integer containing the file unit number.
Keywords
None.
Discussion
GET_LUN sets unit to the first available logical unit number. This number can then be used to open a file.
User-written PV-WAVE functions and procedures should use GET_LUN to reserve unit numbers to avoid conflicts with other routines. (Similarly, they should use FREE_LUN to free them when finished).
 
note
The Get_Lun keyword, used with the OPENR, OPENU, and OPENW procedures, calls GET_LUN to allocate a file unit number.
Example
Suppose that the first available logical unit number is 100.
; Return the logical unit number to allocate (100).
GET_LUN, log_unit
; Open test.dat file for reading. Then read the file.
OPENR, log_unit, !Data_Dir + 'mandril.img'
my_var = BYTARR(512, 512)
READU, log_unit, my_var
; Closes the file and frees the logical unit 100.
FREE_LUN, log_unit
See Also
CLOSE,   FREE_LUN,   ON_IOERROROPEN (UNIX)
OPE
N(Windows)POINT_LUN,   READ,   WRITEU
For background information, see the PV‑WAVE Programmer’s Guide.

Version 2017.0
Copyright © 2017, Rogue Wave Software, Inc. All Rights Reserved.