银行家算法.cpp

一个完整的操作系统的银行家算法 C＋＋源代码

#include "string.h"
#include "iostream.h"
#define M 5           //总进程数
#define N 3           //总资源数
#define FALSE 0
#define TRUE 1

int MAX[M][N]={{7,5,3},{3,2,2},{9,0,2},{2,2,2},{4,3,3}};
int AVAILABLE[N]={10,5,7}; 
int ALLOCATION[M][N]={{0,1,0},{2,0,0},{3,0,2},{2,1,1},{0,0,2}};
int NEED[M][N]={{7,5,3},{3,2,2},{9,0,2},{2,2,2},{4,3,3}};
int Request[N]={0,0,0};


void main()
{
int i=0,j=0;
char flag='Y';
void show();
void changdata(int);
void rstordata(int);
int check(int);

show();
//while(flag=='Y'||flag=='y')
//{
  i=-1;
  while(i<0||i>=M)
  {
   cout<<"请输入需申请资源的进程号（从0到"<<M-1<<"，否则重输入!）:";
   cin>>i;
   if(i<0||i>=M)cout<<"输入的进程号不存在，重新输入!"<<endl;
  }
  cout<<"请输入进程"<<i<<"申请的资源数"<<endl;
  for (j=0;j<N;j++)
  {
   cout<<"资源"<<j<<":  ";
   cin>>Request[j];
   if(Request[j]>NEED[i][j])
   {
    cout<<"进程"<<i<<"申请的资源数大于进程"<<i<<"还需要"<<j<<"类资源的资源量!"<<endl;
		 cout<<"申请失败！";
    flag='N';
    break;
   }
   else
   {
    if(Request[j]>AVAILABLE[j])
    {
     cout<<"  进程"<<i<<"申请的资源数大于系统可用"<<j<<"类资源的资源量!"<<endl;
	 cout<<"申请失败！";
     flag='N';
     break;
    }
   }
  }
  if(flag=='Y'||flag=='y')
  {
   changdata(i);
   if(check(i))
   {
    rstordata(i);
   show();
   }
   else
   show();
  }
  //else
   //showdata();
  //cout<<endl;
  //cout<<"  是否继续银行家算法演示,按'Y'或'y'键继续,按'N'或'n'键退出演示: ";
  //cin>>flag;
//}
}


void show()
{
int i,j;
    cout<<"系统可用的资源数为:"<<endl<<endl;
cout<<"      ";
for (j=0;j<N;j++)cout<<"  资源"<<j<<":  "<<AVAILABLE[j];
    cout<<endl;
   cout<<endl;
cout<<"        各进程还需要的资源量:"<<endl<<endl;
for (i=0;i<M;i++)
{
  cout<<"进程"<<i<<":";
  for (j=0;j<N;j++)cout<<"  资源"<<j<<":  "<<NEED[i][j];
        cout<<endl;
}
    cout<<endl;
cout<<"        各进程已经得到的资源量:  "<<endl<<endl;
for (i=0;i<M;i++)
{
  cout<<"进程"<<i<<":";
  for (j=0;j<N;j++)cout<<"  资源"<<j<<":  "<<ALLOCATION[i][j];
        cout<<endl;
}
    cout<<endl;
};

void changdata(int k)
{
int j;
for (j=0;j<N;j++)
{
  AVAILABLE[j]=AVAILABLE[j]-Request[j];
  ALLOCATION[k][j]=ALLOCATION[k][j]+Request[j];
  NEED[k][j]=NEED[k][j]-Request[j];
}

};

void rstordata(int k)
{
int j;
for (j=0;j<N;j++)
{
  AVAILABLE[j]=AVAILABLE[j]-Request[j];
  ALLOCATION[k][j]=ALLOCATION[k][j]+Request[j];
  NEED[k][j]=NEED[k][j]-Request[j];
}

};

int check(int s)
{
int WORK,FINISH[M],temp[M];
int i,j,k=0;
for(i=0;i<M;i++)FINISH[i]=FALSE;
for(j=0;j<N;j++)
{
WORK=AVAILABLE[j];
i=s;
while(i<M)
{
  if (FINISH[i]==FALSE&&NEED[i][j]<=WORK)
  {
   WORK=WORK+ALLOCATION[i][j];
   FINISH[i]=TRUE;
   temp[k]=i;
   k++;
   i=0;
  }
  else
  {
   i++;
  }
}
for(i=0;i<M;i++)
  if(FINISH[i]==FALSE)
  {
   cout<<endl;
   cout<<"系统不安全!!! 本次资源申请不成功!!!"<<endl;
   cout<<endl;
   return 1;
  }
}
for(i=0;i<M;i++)
  if(FINISH[i]==TRUE)
  {
	  cout<<endl;
cout<<"经安全性检查，系统安全，本次分配成功。"<<endl;
cout<<endl;
cout<<"本次安全序列：";
for(i=0;i<M;i++)cout<<"进程"<<temp[i]<<"->";
cout<<endl<<endl;;
return 0;
};
}