Re: ****ft operator undefined behavior

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Thank you Jack for the tip.

The other workaround that I have found to work on my platform is to
write:

unsigned char m = 32;
register unsigned mask = (static_cast<unsigned long long>(1)<<m)-1;

There is minor clarification I can add to what you wrote. If I am not
wrong, sizeof is a C++ reserved keyword and a builtin operator. Hence,
there should not be any header file defining sizeof.

Greetings,
Olivier Langlois
http://www.olivierlanglois.net
http://blog.olivierlanglois.net

> Example, almost but not universally ****table:
>
> #include <climits>
> /* include at least one header that defines std::sizeof */
>
> unsigned int safe_uint_****ft(unsigned int value, unsigned int bits)
> {
>     if (bits > (CHAR_BIT * std::sizeof(unsigned int)) return 0;
>     else return value << bits;
>
> }
>
> Put it in a header and make it inline if you like.
>
> That is essentially what you are asking he compiler to do for you, but
> many other programs don't want or need the extra check.


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