Hi,
Pls find below the CPP processed source code. I hope you can then make out
how does it work.
main()
{
int abc = (1 = 2);
printf("abc = %d\n",abc);
}
~Abu.
Abu M. Muttalib
Sr. Engineer, Embedded System,
Aftek Infosys Ltd.,
Office: 91-20-25449260-65 X-256
Mobile: (0)9881322820
Email: abum@xxxxxxxxx
-----Original Message-----
From: kernelnewbies-bounce@xxxxxxxxxxxx
[mailto:kernelnewbies-bounce@xxxxxxxxxxxx]On Behalf Of Mukund JB.
Sent: Friday, February 17, 2006 7:02 PM
To: kernelnewbies
Cc: Fawad Lateef
Subject: MACRO - How is it working in Linux
Dear All,
I have seen a macro like this in the Linux kernel sources in
include/linux/usb.h line no: 1090.
#define usb_dotoggle(dev, ep, out) ((dev)->toggle[out] ^= (1 << (ep)))
I did not understand how it works?
I have written a small usermode program to test this.
#define x 1
#define y 2
#define macro() (x = y)
main()
{
int abc = macro();
printf("abc = %d\n",abc);
}
This code results in a compile error.
test.c:9: error: invalid lvalue in assignment.
Why?
Regards,
Mukund Jampala
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--
Kernelnewbies: Help each other learn about the Linux kernel.
Archive: http://mail.nl.linux.org/kernelnewbies/
FAQ: http://kernelnewbies.org/faq/
