Re: Java vs C++ speed (IO & Revisted Again)

From:

"Bo Persson" <bop@gmb.dk>

Newsgroups:

comp.lang.c++,comp.lang.java.programmer

Date:

Sat, 22 Mar 2008 22:35:04 +0100

Message-ID:

<64lcc5F2c6fgdU1@mid.individual.net>

Razii wrote:

This time I used the new java.nio package for reading and writing.
Result (on my comp) are really pathetic for c++ :)

Also, since the program spends most of the time in reading and
writing the file, I removed sorting from both java and C++ version
(it's irrelevant to IO test anyway).

(for one bible.txt)

Time for reading and writing files: 94 ms (java)
Time for reading and writing files: 78 ms (java)
Time for reading and writing files: 63 ms (java)

Time for reading and writing file: 156 ms (c++)
Time for reading and writing file: 156 ms (c++)
Time for reading and writing file: 156 ms (++)
===== C++ Version =======
#include <ctime>
#include <fstream>
#include <iostream>
int main(int argc,char *argv[])
{

  std::ifstream src("bible.txt");
  std::ofstream dst("output.txt");
  clock_t start=clock();
  dst << src.rdbuf();

If you want do double the speed here, replace the line above with:

while(src.good())
{
    char Buffer[1000];

    src.read(Buffer, sizeof Buffer);
    dst.write(Buffer, src.gcount());
}

  clock_t endt=clock();

   std::cout <<"Time for reading and writing file: " <<
      double(endt-start)/CLOCKS_PER_SEC * 1000 << " ms\n";
   return 0;
}

Benchmarks are hard.

Bo Persson