Re: [Dev-C++] Character variables

[Per W. <pw...@ia...>]

The next step of from the 32-bit case statement below would be to use a
hash table.

However, how would you replace the switch statement with std::bitset?

/Per W

On Wed, 5 Mar 2003, Ioannis Vranos wrote:

> -------Original Message-------
>
> From: Per Westermark
> Date: =D4=E5=F4=DC=F1=F4=E7, 5 =CC=DC=F1=F4=E9=EF=F2 2003 12:26:51 =F0=EC
> To: Giligun
> Cc: C++
> Subject: Re: [Dev-C++] Character variables
>
> short s =3D 'ab';
> int i =3D 'abcd';
>
> given that int is 4 byte.
>
>
> =3D=3D> That isn't valid C++. And where it gets compiled you can't consid=
er it
> as safe.
>
>
>
> But a lot of compilers will give you warnings, since it you can't be sure
> if memcpy(buf,&s,sizeof(s)) will give you
> buf[0] =3D 'a', buf[1] =3D 'b';
> or
> buf[0] =3D 'b', buf[1] =3D 'a';
>
> In short - be very careful about using this feature. One place where it's
> elegant to use is if you are reading a tagged file, where each tag is
> 4-byte long:
> char *buf;
>
> int tag =3D 0;
> for (i =3D 0; i < 4; i++) {
> tag =3D (tag << 8) | *buf++;
> }
>
>
> =3D=3D> Too system dependent. Why don't you use wchar_t instead? But sinc=
e he
> wants to store characters (assuming in the range 0-127) he can use a char
> sequence nicely and easily.
>
> switch (tag) {
> case 'STRT': ...; break;
> case 'HEDR': ...; break;
> case 'DATA': ...; break;
> case 'ENDF': ...; break;
> }
>
> If there are a lot of tags, the result is a very fast matching of the
> tags.
>
>
> =3D=3D> By the way i would do something like the above using std::bitset.
>
>
>
> Ioannis Vranos
>
> * Programming pages: http://www.noicys.freeurl.com
> * Alternative URL: http://run.to/noicys