| Using wait in IDL from C [message #7243] |
Fri, 11 October 1996 00:00 |
Karl Young
Messages: 31
Registered: April 1996
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Member |
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I'm using the following code to call IDL from C and
it works fine except that I can't seem to make IDL
wait for keyboard input (e.g. to terminate). For
example if I stick a getchar in, it gets executed before
all the idl commands, regardless of where I put it in
the program and so is useless. It seems the compiler
is seperating all the code I send throught the pipe
and I apparently need to include some kind of
synchronization.
More specifically what I want to do is call IDL and put
up a plot, then wait for some keyboard input to terminate,
so you can view the plot as long as you want. My current
workaround is really ugly; run the process in the background,
send IDL a really long wait after putting up the plot and then
closing the plot window when done viewing (what a trainwreck
if a lot of people tried to use this at once !)
Here's a simple example:
--------------------------------------------------
#include <stdio.h>
FILE *idl;
start_idl()
{
idl = popen("idl >/dev/null 2>&1", "w");
if (idl == NULL) {
printf ("error invoking idl\n");
exit(1);
}
}
stop_idl()
{
pclose(idl);
}
main()
{
char *cmd;
start_idl();
/*
* send commands to idl...
*/
cmd = "num = FindGen(40)*10\n";
fputs(cmd, idl);
cmd = "line = Sin(num * !DtoR)\n";
fputs(cmd, idl);
cmd = "Plot, num , line\n";
fputs(cmd, idl);
/*
* here's where I'd like to pause but currently
* just send a long wait, e.g. wait, 180. If I
* put something like:
* getint = getchar();
* it gets executed before the above idl calls,
* so the program initially just waits and then
* zooms through all the idl calls after any
* keyboard input.
*/
cmd = "exit\n";
fputs(cmd, idl);
stop_idl();
}
------------------------------------------------------------ -
Any suggestions greatly appreciated !
-- Karl Young
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