C programming help ....

[Kevin O'Gorman]

Vu Pham's solution depends on the specifics of your C compiler.
Mine won't allow multi-character constants in that way, at least
not without a warning.  It doesn't like his main() function parameters
either.
A more portable way (though still subject to differences of endianness):

typedef union {
    char bytes[4];
    int code;
} code_t;

int main( int argc, char *argv[] )
{
    code_t b = {'A', 'B', 'C', 'D'};

    printf(" %02x", (b.code >> 24) & 0xFF);
    printf(" %02x", (b.code >> 16) & 0xFF);
    printf(" %02x", (b.code >> 8) & 0xFF);
    printf(" %02x\n", (b.code ) & 0xFF);

    return 0;
}


On 5/19/06, Vu Pham <vu at sivell.com> wrote:
>
> You can use something like
>
> Var = 'LNDE';
>
> And the compiler will pack it in accordingly;
>
> int main( int c, char *args )
> {
> int a = (int)'XYZT';
>         printf( "%02x ", (a&0xFF000000) >> 24 );
>         printf( "%02x ", (a&0x00FF0000) >> 16 );
>         printf( "%02x ", (a&0x0000FF00) >> 8  );
>         printf( "%02x \n", (a&0xFF)  );
>
> }
> [vu at cvs vu]$ ./t
> 58 59 5a 54
> [vu at cvs vu]$
>
>
> -----Original Message-----
> From: linux-users-bounces at linux-sxs.org
> [mailto:linux-users-bounces at linux-sxs.org] On Behalf Of Ben Duncan
> Sent: Friday, May 19, 2006 10:52 AM
> To: Linux tips and tricks
> Subject: C programming help ....
>
> Ok, I am trying to figure out how to "pack" hex strings a 32 bit integer.
> What I need to do is code the following characters.
> "LNDE", "INDE", "RNDE", "DATA", "DEAD" each into a integer.
>
> is the correct way to do this (on a 32 bit machine) thus:
>
> int LNDE_int = 0x4C4E4445 ;         /* Pack 'LNDE' into LNDE_int */
>
> .. and so on and so on ....
>
> Thanks ...
>
>
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>



-- 
Kevin O'Gorman, PhD
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