what are __u32, __u16, __u8 ?

**ashok449** · 03-26-2008

Dear All,

what are __u32, __u16, __u8 ?

Code:

typedef struct a
{
	__u32 ival;
		__u16 ivar;
}b;


b *c;
c->ival=3;

how to print ival/ivar ? which type they are ?

Thanks in advance ...

**vart** · 03-26-2008

this is unsigned integer type with 8,16,32 bits in it...
you can print them all using %u format

PS. on the 16-bit compiler you may need %lu for the last one as it will be probably typedef of unsigned long...

**ashok449** · 03-26-2008

below code showing errors

__u32 undeclared

Code:

#include <stdio.h>
#include <stdlib.h>
int main()
{

__u32 a;
a=12;
printf("__u32 a =&#37;lu", a);

return 0;
}

**vart** · 03-26-2008

below code showing errors

so you do not have these types defined...

**slingerland3g** · 03-26-2008

Are you needing to work with the

asm/types.h

Header file? As I believe those types are defined within.

**Salem** · 03-26-2008

Since the names begin with underscores, it means they're specific to whatever system you're using.
So unless you give us more detail, we can't help.

**ashok449** · 03-27-2008

Thanks for all,

These are all system specific and defined in asm/types.h

thanks ...

**joyjitpyne** · 02-12-2010

In some gcc compilers the header file reqd. may be <sys/types.h>

**cas** · 02-12-2010

As of C99 there are standard fixed width types. If you include stdint.h then you get int8_t, uint8_t, int16_t, uint16_t, etc. These have at least a fighting chance of being portable, since they're standard C, even if it is the newer, less-implemented standard. I'd recommend using stdint.h if you can, since it's less system-specific than types like __u8.

Of course these types need not exist on systems without the "proper" standard types (say a system with 9-bit bytes), but that would be true for __u8, etc. as well.

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