Re: Unions in Obj-C Code

FROM : Steven Noyes
DATE : Wed Apr 04 17:58:36 2007

One thing to watch out for (and you may have it covered) is the crc
[2].  With both PPC and Intel that you have to worry about, make sure 
you keep you Endian Orders right.

Steven

On Apr 3, 2007, at 8:44 PM, Mike wrote:

> Are unions supported in Obj-C? If so is there anything special I 
> have to do to use them?
>
> In my .h file I define a union like this:
>
> typedef struct
> {
>    char        type;
>    char        version;
>    char        oem[ SER_OEM_SIZE ];
>    char        alpha_chk[ 2 ];
>    char        number[ SER_NUM_SIZE ];
>    char        crc[ 2 ];
> } serial_rec;
>
> union serial_buff
> {
>    serial_rec    s;
>    char        c[ sizeof( serial_rec ) ];
> };
>
> I then import that.h file into my .m file but any time I try to use 
> the union I get an error on the declaration of my union serial_buff s:
>
> - (BOOL)_validateSerialNumberAlpha:(char*)pserial_number
> {
>    BOOL            result = NO;
>    serial_buff        s;
>
>    memset( &s, 0, sizeof( s ) );
>      memmove( s.c, pserial_number, ( strlen( pserial_number ) > 
> sizeof( s.c )) ? sizeof( s.c ) : strlen( pserial_number ) );
> .
> .
> .
>
> Thanks,
>
> Mike
>
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