eldo_user

Eldo Control Language
Statement Overview
.define_task hello_world_2
set myfile = NULL
myfile = fopen ("./hello.txt", "w", \
"cannot open hello.txt for writing")
fprint (myfile, "Hello world.\n")
fclose (myfile)
.end_define_task
See “Task Definition” on page 814 and “Variables” on page 821 for more information on the
concepts used in the example.
File type variables are used by the fopen, fprint and fclose commands. The fopen command in
the example above attempts to open the file hello.txt for writing. If this is successful, the logical
name myfile can be used in further commands to reference the file. If for some reason this is not
possible (for example the disk full, access is denied, and so on) the die optional message is
printed to the standard output, and the program aborts. If the file can be opened, then the myfile
name becomes non-NULL, and it can be used in subsequent fprint commands to designate this
particular file. To close the file, the fclose command must be used. The myfile variable is then
automatically set to NULL, and any further attempt to use it in an fprint command will result in
an error.
The stdout logical name can be used to write to the standard output of the calling process
(usually the console). Standard error (stderr) is not supported.
See Library of Functions for Tasks for the complete list of functions operating on file type
variables.
Related Topics
Variables
Library of Functions for Tasks
Predefined Constants
A number of physical constants are available. This is a list of reserved symbols, such as pi,
boltz, and so on. Using these symbols for any purpose (a variable or task for example) is
forbidden.
• epso = 8.854214871×10 −12
• boltz = 1.3806226×10 −23
• charge = 1.6021918×10 −19
• pi = 3.141592654
• twopi = 6.283185308
834
Eldo® User's Manual, 15.3