Reading from a message queue

[Ramon]

Hi,

I'm currently writing a program that tries to read (from a message
queue) either a message of type 123 or a one of type 111.

I've tried the following code but it seems that it is not working:


// reads from the message queue
if ( msgrcv(qid, &mesg, sizeof(mesg), 123 || 111, 1) < 0 )
/** error occurs and halt **/

if (mesg.mtype == 123) {
....
}

else {
....
}


Is there a way to write a code that can read either a message from the
message queue of type A or a one of type B /without/ busy waiting??

Thankx


cc: comp.unix.progr ammer

[Morris Dovey]

Re: Reading from a message queue

Ramon wrote:

I'm currently writing a program that tries to read (from a message
queue) either a message of type 123 or a one of type 111.
>
I've tried the following code but it seems that it is not working:

if ( msgrcv(qid, &mesg, sizeof(mesg), 123 || 111, 1) < 0 )

msgrcv() is a *nix extension. You'll have better luck asking on

cc: comp.unix.progr ammer

--
Morris Dovey
DeSoto Solar
DeSoto, Iowa USA

http://www.iedu.com/DeSoto/

[Ben Bacarisse]

Re: Reading from a message queue

Ramon <ramif_47@yahoo .co.ukwrites:

I'm currently writing a program that tries to read (from a message
queue) either a message of type 123 or a one of type 111.
>
I've tried the following code but it seems that it is not working:
>
// reads from the message queue
if ( msgrcv(qid, &mesg, sizeof(mesg), 123 || 111, 1) < 0 )

The C part of the answer is that writing 123 || 11 there is just like
writing 1 (the way C represents "true") because || is a logical (and
not a bitwise) or operation.

Is there a way to write a code that can read either a message from the
message queue of type A or a one of type B /without/ busy waiting??
>
cc: comp.unix.progr ammer

And there you'll the that other part of the answer (which is "no, not
in general").

--
Ben.