再测JAVA性能比C/C++好问题

   今天我看了《叫嚣JAVA性能比C/C++好的人进来看看，用VC5.0编译没加优化选项的程序都比GCJ优化后生成的JAVA NATIVE CODE快！更别说用INTEL C/C++ 8.0了》

 一贴，感觉测试算法比较有意义，上测试源代码

#include "stdafx.h"
#include <stdio.h>
#include <time.h>


bool isPrime(long i)
{
  for(long test = 2; test < i; test++)
  {
    if(i%test == 0)
    {
      return false;
    }
  }
  return true;
}


void main(void)
{
  clock_t start_time = clock();

  long n_loops =  50000;
  long n_primes = 0;

  for(long i = 0; i < n_loops; i++)
  {
    if(isPrime(i))
    {
      n_primes++;
    }
  }

  clock_t end_time = clock();
  printf("%d primes found\n", n_primes);
  printf("Time taken = %d\n", end_time - start_time);
  getchar();
}

package prime;

import java.io.*;

class prime

{

   private static boolean isPrime(long i)

   {

       for(long test = 2; test < i; test++)

       {

       if(i%test == 0)

       {

        return false;

       }

       }       

       return true;

   }



   public static void main(String[] args) throws IOException

   {

       long start_time = System.currentTimeMillis();



       long n_loops =  50000;

       long n_primes = 0;



       for(long i = 0; i < n_loops; i++)

       {

       if(isPrime(i))

           {

           n_primes++;

           }

       }

   

       long end_time = System.currentTimeMillis();



       System.out.println(n_primes + " primes found");

       System.out.println("Time taken = " + (end_time - start_time));

   }

}

结果：

VC 2012 编译运行结果：
x86
primerelease
5135 primes found
Time taken = 343


5135 primes found
Time taken = 343



x64
primereleasex64
5135 primes found
Time taken = 347


5135 primes found
Time taken = 348


5135 primes found
Time taken = 348


JAVA 运行结果

C:\Users\luozhuang>java -jar G:\test.jar
5135 primes found
Time taken = 1253


C:\Users\luozhuang>java -jar G:\test.jar
5135 primes found
Time taken = 1229


C:\Users\luozhuang>java -jar G:\test.jar
5135 primes found
Time taken = 1257


C:\Users\luozhuang>java -jar G:\test.jar
5135 primes found
Time taken = 1249

机器平台：

C:\Users\luozhuang>java -version
java version "1.7.0_40"
Java(TM) SE Runtime Environment (build 1.7.0_40-b43)
Java HotSpot(TM) 64-Bit Server VM (build 24.0-b56, mixed mode)

C++编译器

vc++ 2012 分x86 和x64两个平台

系统 windows 8 x64

i7 3630qm + 8G 内存