假定循环内用时较多，fun1比fun2快多少

#include <iostream>
using namespace std ;
#include <time.h>
#define WAN (10000)
const int iNum = WAN*300;
void fun1(int* p)
{
    for( int i = 0 ; i < iNum ; i++ )
    {
        p[i] = i;
    }
}
void fun2(int* p)
{
    for( int i = 0 ; i < iNum ; i+= 4  )
    {
        p[i] = i;
        p[i+1] = i+1;
        p[i+2] = i+2;
        p[i+3] = i+3 ;
    }
}
void Test()
{
    int * p = new int[iNum];
    long x1 = clock();
    fun1(p);
    long x2 = clock();
    fun2(p);
    long x3 = clock();
    cout << (x2-x1) << "豪秒 " << (x3-x2) << "豪秒" << endl;
    delete [] p ;
}
void main()
{
   Test();
   Test();
   Test();
   Test();
   Test();
}

#include <iostream>
using namespace std ;
#include <time.h>
#include <math.h>
#define WAN (10000)
const int iNum = WAN*300;
#define NN(n) (pow((float)n,100))
void fun1(int* p)
{
    for( int i = 0 ; i < iNum ; i++ )
    {
        p[i] = NN(i);
    }
}
void fun2(int* p)
{
    for( int i = 0 ; i < iNum ; i+= 4  )
    {
        p[i] = NN(i);
        p[i+1] = NN(i+1);
        p[i+2] = NN(i+2);
        p[i+3] = NN(i+3) ;
    }
}
void Test()
{
    int * p = new int[iNum];
    long x1 = clock();
    fun1(p);
    long x2 = clock();
    fun2(p);
    long x3 = clock();
    cout << (x2-x1) << "豪秒 " << (x3-x2) << "豪秒" << endl;
    delete [] p ;
}
void main()
{
   Test();
   Test();
   Test();
   Test();
   Test();
}