Re: [Dev-C++] Formula question

[Jonathan W. <jon...@gm...>]

On 6/7/07, Philip Bennefall <phi...@pb...> wrote:
>
> Hi,
> Could anyone tell me the formula which is used to calculate the min and
> max values for a numerical data type of x bytes? Say for instance that I use
> the
> sizeof(datatype) function and get the answer 4, which is usually an
> integer, how do I then programatically calculate the min and max values for
> a signed
> and unsigned version of the data type respectively.
> Thanks in advance.
> Regards
> Philip Bennefall
>
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Hi,

Usually there are constants defined for this use, which might be more
useful.

However, this is how to calculate the values, supposing the encoding for
negative number is 2's complement (machines that don't use this are rather
rare, I believe, and won't be running windows...)
Also supposing your data type is some kind of binary integer (floats and
double are encoded differently)
nb_bytes = sizeof(...)
nb_bits = 8*nb_bytes
max_unsigned = 2^nb_bits - 1
min_unsigned = 0 //no kidding !
max_signed = 2^(nb_bits-1) - 1
min_unsigned = -( 2^(nb_bits-1) )

Jonathan

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