操作系统课程设计之存储管理－－－最佳置换算法

				#include 
				
				#define Bsize 4
				
				#define Psize 25
				
				struct pageInfor
				{
				 int content;//页面号
				 int timer;//被访问标记
				};
				
				class PRA
				{
				public:
				    PRA(void);
				 int findSpace(void);//查找是否有空闲内存
				 int findExist(int curpage);//查找内存中是否有该页面
				 int findReplace(void);//查找应予置换的页面
				 void display(void);//显示
				 
				 void Optimal(void);//OPTIMAL算法
				 void BlockClear(void);//BLOCK恢复
				 pageInfor * block;//物理块
				 pageInfor * page;//页面号串
				
				private:
				
				};
				
				PRA::PRA(void)
				{
				 int QString[25]={7,0,1,2,0,3,0,5,2,3,0,3,2,1,2,0,1,7,0,1,4,5,6,7,0};
				
				    block = new pageInfor[Bsize];
				 for(int i=0; i				 {
				  block[i].content = -1;
				  block[i].timer = 0;
				 }
				
				 page = new pageInfor[Psize];
				 for(i=0; i				 {
				  page[i].content = QString[i];
				  page[i].timer = 0;
				 }
				}
				
				
				int PRA::findSpace(void)
				{
				 for(int i=0; i				  if(block[i].content == -1)
				   return i;//找到空闲内存，返回BLOCK中位置
				 return -1;
				}
				
				int PRA::findExist(int curpage)
				{
				
				 for(int i=0; i				  if(block[i].content == page[curpage].content)
				   return i;//找到内存中有该页面，返回BLOCK中位置
				
				 return -1;
				}
				
				int PRA::findReplace(void)
				{
				 int pos = 0;
				
				 for(int i=0; i				  if(block[i].timer >= block[pos].timer)
				   pos = i;//找到应予置换页面，返回BLOCK中位置
				 return pos;
				}
				
				void PRA::display(void)
				{
				
				
				 for(int i=0; i				  if(block[i].content != -1)
				   cout				 cout				}
				
				
				void PRA::Optimal(void)
				{
				 int exist,space,position ;
				
				 for(int i=0; i				 {    
				  exist = findExist(i);
				  if(exist != -1)
				  { cout				  else
				  {   
				   space = findSpace();
				   if(space != -1)
				   {
				    block[space] = page[i];  
				    display();
				   }
				   else
				   {
				     for(int k=0; k				    for(int j=i; j				    {
				     if(block[k].content != page[j].content)
				     { block[k].timer = 10000; }//将来不会用，设置TIMER为一个很大数
				     else
				     {
				      block[k].timer = j;
				      break;
				     }
				    }
				    position = findReplace();   
				    block[position] = page[i];   
				    display();
				   }
				  }
				 }
				}
				
				
				
				void PRA::BlockClear(void)
				{
				 for(int i=0; i				 {
				  block[i].content = -1;
				  block[i].timer = 0;
				 }
				}
				
				
				void main(void)
				{
				 cout				 
				 cout				 cout				 cout				 cout				 
				 cout				 int select;
				 PRA test;
				
				 
				 while(select)
				 {
				  cin>>select;
				  switch(select)
				  {
				   case 0:
				    break;
				   case 1:
				    cout				    test.Optimal();
				    test.BlockClear();
				    cout				    break;
				   }
				  
				 }
				
				}