Re: Cast operation or string conversion?

[Giuseppe:G:]

Victor Bazarov wrote:

A pair of size_t objects is *most likely* bigger than an unsigned int.

HI, Victor, I studied better my code and realised that I can use that
observe function only by passing the uint32 pointer to it (the *string
version does other things). So I guess now I have a more serious
problem, that of uniquely mapping this pair of (size_t size_t) to and
uint32. What do you propose to do?

Is it possible to cast

An idea is to go redefine the observe function using uint64_t instead of
uint32

observe(uint64_t* wordid);

and then convert each size_t into a uint32 and chain them into a uint64.
Does it sound reasonable?Something like this

uint64_t chain(uint32_t one, uint32_t two) {
// get two 32bit rands and concatenate
uint64_t longrand = one;
longrand <<= 32;
longrand |= two;
return longrand;
}

but I have no clue on how to get a uint32 out of a size_t and if it's
feasible.
Can you suggest other ways?

Thanks so much again

Giuseppe

You cannot dynamic_cast anything except pointers to polymorphic classes.
That means the approach you're describing is not going to work.

I would say convert your tuple into a string using hexadecimal or some
other notation and pass the pointer to that string to your 'observe'
function.

BTW, what's the reason you're passing pointers and not references?

V

[Victor Bazarov]

Giuseppe:G: wrote:

Victor Bazarov wrote:

>A pair of size_t objects is *most likely* bigger than an unsigned int.

HI, Victor, I studied better my code and realised that I can use that
observe function only by passing the uint32 pointer to it (the *string
version does other things). So I guess now I have a more serious
problem, that of uniquely mapping this pair of (size_t size_t) to and
uint32. What do you propose to do?

You need to take a close look at the meaning of those size_t values, why
they are paired, what is unique about them. Generally speaking, if they
can have any value and you have no limit of those pairs, then the number
of possible pairs is std::numeric_limits<size_t>::max()^2. If, on the
other hand, the number of combinations is generally limited, then you
could create a mapping by declaring a static map with all size_t pairs
you encounter and an ever-increasing index. Look the pair up, if it's
there, use the index you've assigned to it, if not there, assign a new
index, store the mapping, and 'observe' the new index.

>
Is it possible to cast

An idea is to go redefine the observe function using uint64_t instead of
uint32

observe(uint64_t* wordid);

and then convert each size_t into a uint32 and chain them into a uint64.
Does it sound reasonable?Something like this

uint64_t chain(uint32_t one, uint32_t two) {
// get two 32bit rands and concatenate
uint64_t longrand = one;
longrand <<= 32;
longrand |= two;
return longrand;
}

but I have no clue on how to get a uint32 out of a size_t and if it's
feasible.
Can you suggest other ways?

V
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