RE: sprintf()

[ET T. <et...@mi...>]

oh my... seems that i've forgotten everything from school
thanks Jean.

> -----Original Message-----
> From: Jean Delvare [mailto:de...@en...]
> Sent: Wednesday, 19 September 2001 5:00 PM
> To: ET Tan
> Cc: Prc-Tools-Devel
> Subject: Re: sprintf()
>
>
>
> > Disregard my last message. Can anyone tell me what is wrong with the
> > following:-
> >
> > ----
> > unsigned long ix = 2220000; // a 32-bit variable
> > char hexStr[100];
> >
> > MemSet(hexStr, 100, 0);
> >
> > memset(hexStr, 0, 50);
> > StrIToH(hexStr+StrLen(hexStr), (ix >> 24) & 0xff);
> > hexStr[StrLen(hexStr)] = ':';
> > StrIToH(hexStr+StrLen(hexStr), (ix >> 16) & 0xff);
> > hexStr[StrLen(hexStr)] = ':';
> > StrIToH(hexStr+StrLen(hexStr), (ix >> 8)  & 0xff);
> > hexStr[StrLen(hexStr)] = ':';
> > StrIToH(hexStr+StrLen(hexStr), (ix)       & 0xff);
> > hexStr[StrLen(hexStr)] = ':';
> >
> > WinDrawChars(hexStr, StrLen(hexStr), 5, 20);
> > ----
> >
> > The output was 00000000:00000021:000000DF:000000E0. The
> prefixed zeros are
> > mysterious, anyway, that aside, shouldn't it be
> > 000000E0:000000DF:00000021:00000000 since motorola dragonball
> is big-endian?
>
> Calling both memset and MemSet is useless. The prefixed zeros are probably
> normal. The result itself is perfectly coherent and does *not* depend on
> the processor endianess.
>
> When you write (ix & 0xff), you don't get "the 8 bits on the right side"
> of ix (nor on the left side). You get the 8 least significant bits,
> regardless of the processor endianess. This is pure mathematics, this is
> not hardware related.
>
> > ----
> > unsigned long ix = 2220000; // a 32-bit variable
> > char hexStr[100];
> >
> > MemSet(hexStr, 100, 0);
> > sprintf(hexStr, "%x:%x:%x:%x", (ix >> 24) & 0xff, (ix >> 16) &
> 0xff, (ix >>
> > 8) & 0xff, ix & 0xff);
> >
> > WinDrawChars(hexStr, StrLen(hexStr), 5, 20);
> > ----
> >
> > The output was 0:0:0:21. I don't understand why. Could be that
> I was using
> > sprintf() the wrong way?.
>
> Yes, the wrong way. You try to output a long using %x instead of %lx. If
> you want to use %x, you have to cast each parameter to UInt16 or UInt8.
>
> sprintf(hexStr, "%x:%x:%x:%x", (UInt8)(ix >> 24) & 0xff, (UInt8)(ix >>
> 16) & 0xff, (UInt8)(ix >> 8) & 0xff, (UInt8)ix & 0xff);
>
> You should be using StrPrintF instead of sprintf. Also, please note that
> the MemSet call is useless here.
>
> Hope it helps.
>
> --
>        /~~       Jean "Khali" Delvare
>   -----\_                        mail: de...@en...
>  --------\                http://www.ensicaen.ismra.fr/~delvare/
> ---=ISMRA/- ____________________________________________________
>