sizeof in preprocessor

[Guest]

How can I write this correctly?

#if sizeof(int) < sizeof(my_int)
..............
#endif

I want compile different pieces of code for different platforms

[Nick Hounsome]

Re: sizeof in preprocessor


"<- Chameleon ->" <cham_gss@hotma il.NOSPAM.com> wrote in message
news:c4lv0p$bbl $1@nic.grnet.gr ...[color=blue]
> How can I write this correctly?
>
> #if sizeof(int) < sizeof(my_int)
> .............
> #endif
>
> I want compile different pieces of code for different platforms
>
>[/color]

You can't in the preprocessor but you could use
specialization of templates based on sizeof

[Nick Hounsome]

Re: sizeof in preprocessor


"<- Chameleon ->" <cham_gss@hotma il.NOSPAM.com> wrote in message
news:c4lv0p$bbl $1@nic.grnet.gr ...[color=blue]
> How can I write this correctly?
>
> #if sizeof(int) < sizeof(my_int)
> .............
> #endif
>
> I want compile different pieces of code for different platforms
>
>[/color]

You can't in the preprocessor but you could use
specialization of templates based on sizeof

[Rolf Magnus]

Re: sizeof in preprocessor

- Chameleon - wrote:
[color=blue]
> How can I write this correctly?
>
> #if sizeof(int) < sizeof(my_int)
> .............
> #endif[/color]

You can't. the value of sizeof() is not evaluated by the preprocessor.
Therefore, you can't use it in preprocessor conditionals. You could do:

#include <climits>
#define MY_INT_MAX some_value
#if INT_MAX < MY_INT_MAX
//something
#else
//something else
#endif

or you use templates: (untested)

template <bool b>
void my_function_int ernal()
{
//something
}

template <>
void my_function_int ernal<false>()
{
//something else
}

void my_function()
{
my_function_int ernal<(sizeof(i nt) < sizeof(my_int)) >();
}

[Rolf Magnus]

Re: sizeof in preprocessor

- Chameleon - wrote:
[color=blue]
> How can I write this correctly?
>
> #if sizeof(int) < sizeof(my_int)
> .............
> #endif[/color]

You can't. the value of sizeof() is not evaluated by the preprocessor.
Therefore, you can't use it in preprocessor conditionals. You could do:

#include <climits>
#define MY_INT_MAX some_value
#if INT_MAX < MY_INT_MAX
//something
#else
//something else
#endif

or you use templates: (untested)

template <bool b>
void my_function_int ernal()
{
//something
}

template <>
void my_function_int ernal<false>()
{
//something else
}

void my_function()
{
my_function_int ernal<(sizeof(i nt) < sizeof(my_int)) >();
}

[Jeff Schwab]

[OT] Re: sizeof in preprocessor

<- Chameleon -> wrote:[color=blue]
> How can I write this correctly?
>
> #if sizeof(int) < sizeof(my_int)
> .............
> #endif
>
> I want compile different pieces of code for different platforms
>
>[/color]

I'd love to answer this for you, but since I'm Jewish, I assume you
don't want my help.

http://groups.google.com/groups?q=chameleon+%22i+hate+jews+too%22&hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=c468hi%245q3%241%40nic.grnet.gr&rnum=1

[Jeff Schwab]

[OT] Re: sizeof in preprocessor

<- Chameleon -> wrote:[color=blue]
> How can I write this correctly?
>
> #if sizeof(int) < sizeof(my_int)
> .............
> #endif
>
> I want compile different pieces of code for different platforms
>
>[/color]

I'd love to answer this for you, but since I'm Jewish, I assume you
don't want my help.

http://groups.google.com/groups?q=chameleon+%22i+hate+jews+too%22&hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=c468hi%245q3%241%40nic.grnet.gr&rnum=1

[Guest]

Re: [OT] Re: sizeof in preprocessor

> > How can I write this correctly?[color=blue][color=green]
> >
> > #if sizeof(int) < sizeof(my_int)
> > .............
> > #endif
> >
> > I want compile different pieces of code for different platforms
> >
> >[/color]
>
> I'd love to answer this for you, but since I'm Jewish, I assume you
> don't want my help.[/color]

your answer is off-topic

[Guest]

Re: [OT] Re: sizeof in preprocessor

> > How can I write this correctly?[color=blue][color=green]
> >
> > #if sizeof(int) < sizeof(my_int)
> > .............
> > #endif
> >
> > I want compile different pieces of code for different platforms
> >
> >[/color]
>
> I'd love to answer this for you, but since I'm Jewish, I assume you
> don't want my help.[/color]

your answer is off-topic

[Jeff Schwab]

Re: [OT] Re: sizeof in preprocessor

<- Chameleon -> wrote:[color=blue][color=green][color=darkred]
>>>How can I write this correctly?
>>>
>>>#if sizeof(int) < sizeof(my_int)
>>>............ .
>>>#endif
>>>
>>>I want compile different pieces of code for different platforms
>>>
>>>[/color]
>>
>>I'd love to answer this for you, but since I'm Jewish, I assume you
>>don't want my help.[/color]
>
>
> your answer is off-topic
>
>[/color]

Yes, that's what [OT] in the subject line means.

[Jeff Schwab]

Re: [OT] Re: sizeof in preprocessor

<- Chameleon -> wrote:[color=blue][color=green][color=darkred]
>>>How can I write this correctly?
>>>
>>>#if sizeof(int) < sizeof(my_int)
>>>............ .
>>>#endif
>>>
>>>I want compile different pieces of code for different platforms
>>>
>>>[/color]
>>
>>I'd love to answer this for you, but since I'm Jewish, I assume you
>>don't want my help.[/color]
>
>
> your answer is off-topic
>
>[/color]

Yes, that's what [OT] in the subject line means.