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digitalmars.D.learn - A puzzle (easy one)

reply "Koroskin Denis" <2korden gmail.com> writes:
Write a one-line compile-time function (or template) that returns a  
number, which can be written in binary as 010101010...010101. Exactly the  
same code should work for byte, short, int, long, cent etc.

No loops or recursion allowed. Use nothing but brain! :)
Aug 06 2008
next sibling parent reply BCS <ao pathlink.com> writes:
Reply to Koroskin,


 Write a one-line compile-time function (or template) that returns a
 number, which can be written in binary as 010101010...010101. Exactly
 the  same code should work for byte, short, int, long, cent etc.
 
 No loops or recursion allowed. Use nothing but brain! :)
 



template it(T)
{
T it = 0x5555_5555_5555_5555_5555_5555_5555_5555_5555_5555_5555_5555
5555_5555_5555_5555 
& (t.max | t.min);
}
Aug 06 2008
parent reply Wyverex <wyverex.cypher gmail.com> writes:
BCS wrote:

 Reply to Koroskin,
 

 Write a one-line compile-time function (or template) that returns a
 number, which can be written in binary as 010101010...010101. Exactly
 the  same code should work for byte, short, int, long, cent etc.

 No loops or recursion allowed. Use nothing but brain! :)



 template it(T)
 {
 T it = 
 0x5555_5555_5555_5555_5555_5555_5555_5555_5555_5555_5555_5555
5555_5555_5555_5555 
 & (t.max | t.min);
 }
Aug 06 2008
parent reply Wyverex <wyverex.cypher gmail.com> writes:
Wyverex wrote:

 BCS wrote:

 Reply to Koroskin,


 Write a one-line compile-time function (or template) that returns a
 number, which can be written in binary as 010101010...010101. Exactly
 the  same code should work for byte, short, int, long, cent etc.

 No loops or recursion allowed. Use nothing but brain! :)



 template it(T)
 {
 T it = 
 0x5555_5555_5555_5555_5555_5555_5555_5555_5555_5555_5555_5555
5555_5555_5555_5555 
 & (t.max | t.min);
 }







template crazy( T )
{
   T crazy =  0xAAAA_AAAA_AAAA_AAAA;
}

as long as the hex string is less then ulong.max ...  or ucent.max when 
that gets implemented...
Aug 06 2008
parent reply Frank Benoit <keinfarbton googlemail.com> writes:
Wyverex schrieb:

 Wyverex wrote:

 BCS wrote:

 Reply to Koroskin,


 Write a one-line compile-time function (or template) that returns a
 number, which can be written in binary as 010101010...010101. Exactly
 the  same code should work for byte, short, int, long, cent etc.

 No loops or recursion allowed. Use nothing but brain! :)



 template it(T)
 {
 T it = 
 0x5555_5555_5555_5555_5555_5555_5555_5555_5555_5555_5555_5555
5555_5555_5555_5555 
 & (t.max | t.min);
 }






 
 template crazy( T )
 {
   T crazy =  0xAAAA_AAAA_AAAA_AAAA;
 }
 
 as long as the hex string is less then ulong.max ...  or ucent.max when 
 that gets implemented...



template func( T ) { T func = mixin( "0x555555555555555555555555"[0 .. 
T.sizeof*2+2] ); }
Aug 06 2008
next sibling parent reply Frank Benoit <keinfarbton googlemail.com> writes:
Koroskin Denis schrieb:

 On Thu, 07 Aug 2008 05:59:30 +0400, Frank Benoit 
 <keinfarbton googlemail.com> wrote:
 

 Wyverex schrieb:

 Wyverex wrote:

 BCS wrote:

 Reply to Koroskin,


 Write a one-line compile-time function (or template) that returns a
 number, which can be written in binary as 010101010...010101. Exactly
 the  same code should work for byte, short, int, long, cent etc.

 No loops or recursion allowed. Use nothing but brain! :)



 template it(T)
 {
 T it = 
 0x5555_5555_5555_5555_5555_5555_5555_5555_5555_5555_5555_5555
5555_5555_5555_5555 
 & (t.max | t.min);
 }






 {
   T crazy =  0xAAAA_AAAA_AAAA_AAAA;
 }
  as long as the hex string is less then ulong.max ...  or ucent.max 
 when that gets implemented...



 template func( T ) { T func = mixin( "0x555555555555555555555555"[0 .. 
 T.sizeof*2+2] ); }



 No-no-no. It should work for integer type of *any* length (byte, short, 
 long, cent and any future type).
 And there is a *much* simpler solution!



right.
template func( T ) { T func = T.max/3; }
Aug 07 2008
parent Frank Benoit <keinfarbton googlemail.com> writes:
Koroskin Denis schrieb:


 right.
 template func( T ) { T func = T.max/3; }



 Doesn't work for signed types :P
 But you are close!



template func( T ) { T func = T.min < 0 ? T.max/3*2+1 : T.max/3; }
Aug 07 2008
prev sibling parent BCS <ao pathlink.com> writes:
Reply to Frank,


 func( T ) { T func = mixin( "0x555555555555555555555555"[0 .. T.sizeof*2+2] 




 




Gaaahhh!!! My eyes <G>
Aug 08 2008
prev sibling next sibling parent "Koroskin Denis" <2korden gmail.com> writes:
On Thu, 07 Aug 2008 05:59:30 +0400, Frank Benoit  
<keinfarbton googlemail.com> wrote:


 Wyverex schrieb:

 Wyverex wrote:

 BCS wrote:

 Reply to Koroskin,


 Write a one-line compile-time function (or template) that returns a
 number, which can be written in binary as 010101010...010101. Exactly
 the  same code should work for byte, short, int, long, cent etc.

 No loops or recursion allowed. Use nothing but brain! :)



 template it(T)
 {
 T it =  
 0x5555_5555_5555_5555_5555_5555_5555_5555_5555_5555_5555_5555
5555_5555_5555_5555  
 & (t.max | t.min);
 }






 {
   T crazy =  0xAAAA_AAAA_AAAA_AAAA;
 }
  as long as the hex string is less then ulong.max ...  or ucent.max  
 when that gets implemented...



 template func( T ) { T func = mixin( "0x555555555555555555555555"[0 ..  
 T.sizeof*2+2] ); }



No-no-no. It should work for integer type of *any* length (byte, short,  
long, cent and any future type).
And there is a *much* simpler solution!
Aug 07 2008
prev sibling parent "Koroskin Denis" <2korden gmail.com> writes:
On Thu, 07 Aug 2008 18:11:27 +0400, Frank Benoit  
<keinfarbton googlemail.com> wrote:


 Koroskin Denis schrieb:

 On Thu, 07 Aug 2008 05:59:30 +0400, Frank Benoit  
 <keinfarbton googlemail.com> wrote:


 Wyverex schrieb:

 Wyverex wrote:

 BCS wrote:

 Reply to Koroskin,


 Write a one-line compile-time function (or template) that returns a
 number, which can be written in binary as 010101010...010101.  
 Exactly
 the  same code should work for byte, short, int, long, cent etc.

 No loops or recursion allowed. Use nothing but brain! :)



 template it(T)
 {
 T it =  
 0x5555_5555_5555_5555_5555_5555_5555_5555_5555_5555_5555_5555
5555_5555_5555_5555  
 & (t.max | t.min);
 }



 overflow...



 {
   T crazy =  0xAAAA_AAAA_AAAA_AAAA;
 }
  as long as the hex string is less then ulong.max ...  or ucent.max  
 when that gets implemented...



 template func( T ) { T func = mixin( "0x555555555555555555555555"[0 ..  
 T.sizeof*2+2] ); }



 short, long, cent and any future type).
 And there is a *much* simpler solution!



 right.
 template func( T ) { T func = T.max/3; }



Doesn't work for signed types :P
But you are close!
Aug 07 2008