Re: To go with Go or C/C++?

From:
Martin Shobe <martin.shobe@travelport.com>
Newsgroups:
comp.lang.c++
Date:
Sun, 05 May 2013 21:10:26 -0500
Message-ID:
<km737u$2ta$1@dont-email.me>
On 5/5/2013 1:17 PM, Rui Maciel wrote:

???? Tiib wrote:

This is easy to test.


It is.

<code>
#include <cstdio>
#include <ctime>

int ms_elapsed( clock_t start, clock_t stop )
{
         return static_cast<int>( 1000.0 * ( stop - start ) / CLOCKS_PER_SEC
);
}

bool checkThingsWithIf( int param )
{
         return param % 10000 != 0;
}

void checkThingsWithTry( int param )
{
         if ( param % 10000 == 0 )
         {
                 throw true;
         }
}

int testWithIf( int param )
{
         int ret = 0;
         for ( int j = 0; j < 200; ++j )
         {
                 if ( !checkThingsWithIf( param+j ) )
                 {
                         return ret;
                 }
                 ++ret;
         }
         return ret;
}

int testWithTry( int param )
{
         int ret = 0;
         try
         {
                 for ( int j = 0; j < 200; ++j )
                 {
                         checkThingsWithTry( param+j );
                         ++ret;
                 }
         }
         catch ( bool )
         { }
         return ret;
}

void benchmark( int (*foo)(int))
{
         clock_t volatile start;
         clock_t volatile stop;
         int volatile sum;

         start = clock();
         sum = 0;
         for ( int i = 0; i < 1000000; ++i )
         {
                 sum += (*foo)( i );
         }
         stop = clock();
         printf( "It took %d msec; (sum %d)\n", ms_elapsed( start,stop) , sum
);
}

void benchmark( int (*foo)(int))
{
         clock_t volatile start;
         clock_t volatile stop;
         int volatile sum;

         start = clock();
         sum = 0;
         for ( int i = 0; i < 1000000; ++i )
         {
                 sum += (*foo)( i );
         }
         stop = clock();
         printf( "It took %d msec; (sum %d)\n", ms_elapsed( start,stop) , sum
);
}

int main( int argc, char* argv[] )
{
         benchmark( &testWithTry);
         benchmark( &testWithIf);
}
</code>

<output>
rui@kubuntu:tmp$ g++ -O0 main.c++ && ./a.out
It took 2130 msec; (sum 197990000)
It took 2280 msec; (sum 197990000)
rui@kubuntu:tmp$ g++ -O1 main.c++ && ./a.out
It took 1150 msec; (sum 197990000)
It took 1050 msec; (sum 197990000)
rui@kubuntu:tmp$ g++ -O2 main.c++ && ./a.out
It took 1160 msec; (sum 197990000)
It took 670 msec; (sum 197990000)
rui@kubuntu:tmp$ g++ -O3 main.c++ && ./a.out
It took 700 msec; (sum 197990000)
It took 670 msec; (sum 197990000)
</output>

Rui Maciel


Yes, we get it. On if and an exception is usually slower than just an
if. (Not really sure what that adds to the rest of the discussion though.)

Martin Shobe

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