关于FIFO、LRU、OPT页面置换算法的缺页中断率

传说52童鞋的Database Buffer Manager做的有声有色~

今天我也发一个页面置换的OOXX~

代码不长，结构简单~ 高手们退散吧

#include<iostream.h>
#define  M  40
int N;
struct Pro
{
    int num,time;
};
int Input(int m,Pro p[M])
{  
    cout<<"请输入实际页数：";
    do
    {
        cin>>m;
        if(m>M)cout<<"数目太多，请重试"<<endl;
        else break;
    }while(1);
    cout<<endl<<"请输入各页面号"<<endl;
       for(int i=0;i<m;i++)
    {
        cin>>p[i].num;
        p[i].time=0;
    }
    return m;
}

void print(Pro *page1)//打印当前的页面
{
    Pro *page=new Pro[N];
    page=page1;
    for(int i=0;i<N;i++)cout<<page[i].num<<"  ";
    cout<<endl;
}

int  Search(int e,Pro *page1  )
{
    Pro *page=new Pro[N];
    page=page1;
    for(int i=0;i<N;i++)if(e==page[i].num)return i;
    return -1;
}

int Max(Pro *page1)
{
    Pro *page=new Pro[N];
    page=page1;
    int e=page[0].time,i=0;
    while(i<N)//找出离现在时间最长的页面
    {
        if(e<page[i].time)e=page[i].time;
        i++;
    }
    for( i=0;i<N;i++)if(e==page[i].time)return i;
   
    return -1;
}

int Compfu(Pro *page1,int i,int t,Pro p[M])
{
    Pro *page=new Pro[N];
    page=page1;
   
    int count=0;
    for(int j=i;j<M;j++)
    {
        if(page[t].num==p[j].num )break;
        else count++;
    }
    return count;
   
}

int main()
{
   
    cout<<"可用内存页面数"<<endl;
    cin>>N;   
    Pro p[M];
    Pro *page=new Pro[N];
    char c;
    int m=0,t=0;
    float n=0;
    m=Input(m,p);   
   
    do{
       
        for(int i=0;i<N;i++)//初试化页面基本情况
        {
            page[i].num=0;
            page[i].time=2-i;
        }
        /*int j=0,count=1;
        page[0].num=p[0].num;
        int i=1,k=1;
        while(i<N)
        {
        int flag=1;
        for(j=0;j<i;j++)
        if(p[k].num==page[i].num)
        {n++;flag=0;break;}
        if(flag==1){page[i].num=p[k].num;i++;}
        count++;k++;
    }*/
        i=0;       
        cout<<"f:FIFO页面置换"<<endl;
        cout<<"l:LRU页面置换"<<endl;
        cout<<"o:OPT页面置换"<<endl;
        cout<<"按其它键结束"<<endl;
        cin>>c;
       
        if(c==\’f\’)//FIFO页面置换
        {
            n=0;
            cout<<"页面置换情况:   "<<endl;
            while(i<m)
            {
                if(Search(p[i].num,page)>=0)i++;//找到相同的页面
                else
                { 
                    if(t==N)t=0;
                    else
                    {
                        n++;//
                        page[t].num=p[i].num;
                        print(page);
                        t++;
                    }
                }
            }
            cout<<"缺页次数："<<n<<"    缺页率："<<n/m<<endl;     
           
        }
        if(c==\’l\’)//LRU页面置换
        {    n=0;
        cout<<"页面置换情况:   "<<endl;
        while(i<m)
        {   
            int k;
            k=t=Search(p[i].num,page);
            if(t>=0)
               
                page[t].time=0;
           
           
            else
            { 
                n++;
                t=Max(page);
               
                page[t].num=p[i].num;
                page[t].time=0;
            }
            if(t==0){page[t+1].time++;page[t+2].time++;}
            if(t==1){page[2].time++;page[0].time++;}
            if(t==2){page[1].time++;page[0].time++;}
            if(k==-1)   print(page);               
            i++;
        }
        cout<<"缺页次数："<<n<<"    缺页率："<<n/m<<endl;
        }
        if(c==\’o\’)//OPT页面置换
        {
            n=0;
            while(i<m)
            {
                if(Search(p[i].num,page)>=0)i++;
                else
                {
                    int temp=0,cn;
                    for(t=0;t<N;t++)
                    {
                        if(temp<Compfu(page,i,t,p))
                        {
                            temp=Compfu(page,i,t,p);
                            cn=t;
                        }
                    }
                    page[cn]=p[i];
                    n++;
                    print(page);
                    i++;
                }
            }
            cout<<"缺页次数："<<n<<"    缺页率："<<n/m<<endl;
        }
       
    }while(c==\’f\’||c==\’l\’||c==\’o\’);
   
   
   
    return 0;
}