Commenting out a print slows my code?

Hi, all. I'm in college, taking a freshman-level CS class. (I'm actually a
senior chemist with free time.)
Anyhoo, the warm-up assignment was Hardy Taxi problem, phrased like this:
[Exposition removed.] 1729 is the smallest number such that for
(a!=b!=c!=d)>0, there exists a combination of a, b, c, and d where a^3+b^3 =
1729 = c^3+d^3.
The task was to find all other numbers with this property less than 25,000.
The code is basically

for (int iters = 1; iters <= 25_000; iters++){
   if(isTaxiNumber(iters)){
      writefln("%s is a taxi number", iters);
   }
}

(There's also a StopWatch timing things, and isTaxiNumber returns a struct,
not a bool. See attached code.)
This code runs in about 0.09 seconds.
If I comment out the writefln, it takes 0.11 seconds.
(These are collected from about 20 runs of each. Times are very consistent.)
Any ideas why commenting out the write makes things slower?
Cheers,
Charles.

March 10, 2011

Re: Commenting out a print slows my code?

Posted by spir
in reply to Charles McAnany

Permalink

spir

Posted in reply to Charles McAnany

Permalink

On 03/10/2011 01:44 AM, Charles McAnany wrote:
> Hi, all. I'm in college, taking a freshman-level CS class. (I'm actually a
> senior chemist with free time.)
> Anyhoo, the warm-up assignment was Hardy Taxi problem, phrased like this:
> [Exposition removed.] 1729 is the smallest number such that for
> (a!=b!=c!=d)>0, there exists a combination of a, b, c, and d where a^3+b^3 =
> 1729 = c^3+d^3.
> The task was to find all other numbers with this property less than 25,000.
> The code is basically
>
> for (int iters = 1; iters<= 25_000; iters++){
>     if(isTaxiNumber(iters)){
>        writefln("%s is a taxi number", iters);
>     }
> }
>
> (There's also a StopWatch timing things, and isTaxiNumber returns a struct,
> not a bool. See attached code.)
> This code runs in about 0.09 seconds.
> If I comment out the writefln, it takes 0.11 seconds.
> (These are collected from about 20 runs of each. Times are very consistent.)
> Any ideas why commenting out the write makes things slower?

No idea.

But more idiomatic D would rather b:
    foreach (n ; 1..25000)
        {...}

Also I don't understand why your loop var is called 'iters'.

Finally, the attachment is not readible by me: see below.

Denis

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> M(`T*:6UP;W)T('-T9"YS=&1I;SL@+R]P<FEN=&EN9RX@#0HO+R\@02!S=')U
> M8W0@=&AA="!R97!R97-E;G1S(&$@8V%B+B!)="!D;V5S;B=T(&1O('1H92!C
> M:&5C:VEN9R!T:&%T('1H92!O;F4@:6X@=&AE(&%S<VEG;FUE;G0@9&]E<RP@
> M=&AO=6=H+B`-"G-T<G5C="!T87AI0V%B>PT*"6EN="!T87AI3G5M8F5R.PT*
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> M=7)N(&9O<FUA="@B8V%R("5S(#T@6R5S("5S("5S("5S72(L=&%X:4YU;6)E
> M<BP@82P@8BP@8RP@9"D[#0H)?0T*?0T*#0HO*BH-"BH@4')O9W)A;2!T:&%T
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> M<F%M971E<G,Z(`T**B!N(&ES(&%N(&EN=&5G97(@=&AA="!I<R!T;R!B92!C
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> M;'1S6VAI=',@*B`R("L@,5T@/2!N96%R97-T26YT.PT*"0D)?0T*"0D):&ET
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> `
> end

-- 
_________________
vita es estrany
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