RE: [Dev-C++] Can I handle 64 bits with unsigned long long int ?

[Ioannis V. <iv...@em...>]

> -----Original Message-----
> From: Ioannis Vranos [mailto:iv...@em...] 
> Sent: Sunday, April 06, 2003 12:01 PM
> To: 'Dev-C++ -Users-List'
> Subject: RE: [Dev-C++] Can I handle 64 bits with unsigned 
> long long int ?
> 
> 
> Question about C99. That is a first! See below:
> 
> 
> 
> > -----Original Message-----
> > From: dev...@li... 
> > [mailto:dev...@li...] On Behalf 
> > Of Roberto Ricardi
> > Sent: Sunday, April 06, 2003 2:11 AM
> > To: 'Dev-C++ -Users-List'
> > Subject: [Dev-C++] Can I handle 64 bits with unsigned long 
> long int ?
> > 
> > 
> > Hi all,
> > 
> > Can I handle 64 bits numbers with unsigned long long ?
> > 
> > #include <stdio.h>
> > #include <stdlib.h>
> > #include <conio.h>
> > 
> > unsigned long long int D0,D1 ;
> >         
> > int main(int argc, char *argv[])
> > {
> >   D0 = 0;
> >   D1 = 0xffffffffffff; /*  I put first unsigned long int, compiler 
> > alerts about truncated number...) */
> >   gotoxy(1,9);printf ("Num hexa : ");
> >   scanf ("%x",&D0); /*can handle whatever up to 32 bits*/
> >   gotoxy(1,11);printf ("Dec0: %lu\nDec1: %lu\n\n", D0, D1);
> >  
> >   getchar();  getchar();
> >   return 0;
> > }
> > /*
> > Results:
> > 
> > Dec0 : 4294967295 mean ok if I put just up to 0xffffffff  32bits
> > Dec1 : 0  ??
> > */
> > 
> > Why is ever truncated in 32 bits, how can handle long long to 
> > get up to 
> > 64 bits numbers ?
> 
> 
> unsigned long long is not guaranteed to be 64-bit. If you 
> want an unsigned integral type to be at least 64-bit, you have to do:
> 
> 
> #include <stdint.h>
> 
> // ...
> 
> uint_least64_t D0, D1;
> 
>  // ...
> 
> 
> 
> which is a typedef of the closest to 64-bit type provided by 
> platform (closest from above, that is if unsigned long is 32 
> bit and unsigned long long is 128 bit for example, the 
> typedef will be of unsigned long long).
> 
> 
> I read it straight from the standard. I do not know whether 
> MINGW has implemented it (and as far as I know these 
> facilities are "optional", if the platform doesn't support 
> >=64 bit, will not have the above type naturally).
> 
> 
> By the way, have you got any book regarding C99? If yes, can 
> you please tell me which?


I checked and saw that MINGW's long long types are 64-bit. You made a
mistake in the format specifier of printf(). Thus an example code of
printf() printing an unsigned long long value is:

#include <stdio.h>
#include <limits.h>


int main(void)
{
  printf ("Maximum value of unsigned long long: %llu\n", ULLONG_MAX);

  getchar();
}



For the above to compile you must be careful with the compiler switches.




Ioannis Vranos
 
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