C++实现计算机操作系统银行家算法

/*==========================================程序功能：实现银行家算法(假设进程和资源的初始状态为安全)程序编写：sunxden编写日期:2010-11-11编译环境: Windows 7, VC++ 2005 SP6==========================================*//*此程序存在的不足： 1.进程初始状态是否安全判断过后，如果不安全，在主函数里面少了对应的处理方法，比如说重新输入机制。 2.当某一进程请求资源后存在安全序列，如何输出各进程的资源状况没有相应的实现模块。请有心读者自行完善。*/#include<iostream>#include<cstdlib>using namespace std;//定义银行家算法必要的数据结构struct MD{int *Available;int **Max;int **Need;int **Allocation;};//函数声明void Memory_allocated(int ,int ,struct MD *); // 内存分配void Initializated(int , int , struct MD* ); // 对结构体里面的数组进行初始化void Intial_status_is_safe(int ,int ,struct MD* ); // 进程初始状态是否安全void Banker_alogrithm(int , int ,int , int * ,struct MD *); //银行家算法实现void Memory_freed(int ,int , struct MD *); // 内存释放void Menu();int main(){char ch('c');int p , r ,flag(0),*request; // flag为进程标识, request 为资源请求向量cout<<"请输入进程数和资源数: ";cin>>p>>r;if(0 == p || 0 == r){cout<<"进程数或者资源数不等于0 !"<<endl;exit(1);}struct MD *MatrixData = new struct MD; // 定义结构体变量的名字 MatrixData，并分配内存request = new int [r];Memory_allocated(p,r,MatrixData);Initializated(p,r,MatrixData); Intial_status_is_safe(p, r, MatrixData);// 用循环实现菜单功能while(ch != 'e'){switch(ch){ case 'c':{ cout<<"请输入即将请求的资源进程号(0 - "<<p-1<<"): "; cin>>flag; cout<<"请输入请求向量request["<<r<<"]: "; for(int i = 0; i < r; i++){ cin>>request[i];} Banker_alogrithm(p,r,flag,request,MatrixData); break;} case 'e': break;default:cout<<"输入非法, 请重新输入。"<<endl;} Menu(); cout<<"请选择操作: "; while((ch=getchar())!='/n'&& ch!=EOF); //消除缓冲区控制字符的影响ch=getchar();} Memory_freed(p,r,MatrixData);delete[] request;delete MatrixData;MatrixData=NULL; //将指针置空 system("pause");return 0;}void Menu(){cout<<endl;cout<<"/t*****==============OPRATE MENU==================*****"<<endl;cout<<"/t* *"<<endl;cout<<"/t* c-continue e-exit *"<<endl;cout<<"/t*****===========================================*****"<<endl;}void Memory_allocated(int n,int m,struct MD *matrix_data){matrix_data->Available = new int [m];matrix_data->Allocation = new int *[n];matrix_data->Max = new int *[n];matrix_data->Need = new int *[n];for(int i = 0; i < n; i++){matrix_data->Allocation[i]= new int [m];matrix_data->Max[i] = new int [m];matrix_data->Need[i] = new int [m];}}void Initializated(int n, int m, struct MD *matrix_data){int i(0),j(0);cout<<"初始化最大资源需求矩阵Max["<<n<<"]["<<m<<"] :"<<endl;for(i = 0; i < n; i++)for(j = 0; j < m; j++)cin>>matrix_data->Max[i][j];cout<<"初始化资源分配矩阵Allocation["<<n<<"]["<<m<<"] :"<<endl;for(i = 0; i < n; i++ )for(j = 0; j < m; j++)cin>>matrix_data->Allocation[i][j];cout<<"初始化资源需求矩阵Need["<<n<<"]["<<m<<"] :"<<endl;for(i = 0; i < n; i++){for(j = 0; j < m; j++){matrix_data->Need[i][j]=matrix_data->Max[i][j] - matrix_data->Allocation[i][j];cout<<matrix_data->Need[i][j]<<" ";}cout<<"/n";}cout<<"初始化可利用资源向量Available["<<m<<"] : "<<endl;for(i = 0; i < m; i++)cin>>matrix_data->Available[i];}void Intial_status_is_safe(int n,int m,struct MD* matrix_data){int flag; // 标识进程初始状态的变量for(int i = 0; i < n; i++){flag = 1;for( int j = 0; j < m; j++){ //初始状态的可利用资源available[*]是否 >= 任一个进程需求资源need[*][*],是则为安全状态(flag=1);否则不安全(flag=0)if(matrix_data->Available[j] < matrix_data->Need[i][j])flag = 0;}if( 1 == flag){cout<<"进程的初始状态安全。"<<endl;break;}}if(0 == flag )cout<<"进程的初始状态不安全。"<<endl;}// 请求资源向量request[*]是否小于或等于需求资源need[*][*]，是则返回1;否则返回0int Request_less_or_equal_need(int m, int f,int *req, struct MD *matrix_data){for(int i = 0; i < m; i++)if(req[i] > matrix_data->Need[f][i]){return 0;break;}return 1;}// 请求资源request[*]是否小于或者等于可利用资源available[*], 是则返回1;否则返回0int Request_less_or_equal_available(int m, int f, int *req, struct MD *matrix_data){for(int i = 0; i < m; i++)if(req[i] > matrix_data->Available[i]){return 0;break;}return 1;}// 试着给请求资源的进程分配资源void Try_to_allocated_resources(int m, int f, int *req, struct MD *matrix_data){for(int i = 0; i < m; i++){matrix_data->Available[i] = matrix_data->Available[i] - req[i];matrix_data->Allocation[f][i] = matrix_data->Allocation[f][i] + req[i];matrix_data->Need[f][i] = matrix_data->Need[f][i] - req[i];}}//试着分配资源后，判断进程是否存在安全序列int Is_security_or_not(int n,int m,int f,struct MD *matrix_data,int *work,bool *finish,int *order){int i(0), j(0), flag ; // flag变量标识某一进程安全for(i = 0; i < m; i++)work[i] = matrix_data->Available[i]; // work为工作向量, work[*] = availabe[*]for(i = f; i < n ;i++){// finish[i]=false时，才判断是否为安全进程if(false == finish[i]){ flag = 0; for(j = 0; j < m; j++){ // 在进程 i 中，若需求资源need[i][*] > 工作向量work[*],则flag=1，表示此进程暂时不能保证安全，需下次判断。 if( matrix_data->Need[i][j] > work[j]){ flag = 1; break;}} if(0 == flag){ for(j = 0; j < m; j++){ work[j] = work[j] + matrix_data->Allocation[i][j];} finish[i] = true; *order++ = i; //将安全的进程号依次存入数组order中，便天安全序列的输出 i = -1; //置i的值为-1，然后执行for循环条件3: i++ 后，i=0。}}}//执行完毕后,flag要么 = 1, 要么 = 0if(1 == flag)return 0;elsereturn 1;}//若为不安全资源请求，则恢复资源状态，取消资源试分配的影响void Restore(int m,int f, int *req,struct MD *matrix_data){for(int i = 0; i < m; i++){matrix_data->Available[i] = matrix_data->Available[i] + req[i];matrix_data->Allocation[f][i] = matrix_data->Allocation[f][i] - req[i];matrix_data->Need[f][i] = matrix_data->Need[f][i] + req[i];}}void Memory_freed(int n,int m, struct MD *matrix_data){for(int i = 0; i < n; i++){delete [] matrix_data->Max[i];delete [] matrix_data->Allocation[i];delete [] matrix_data->Need[i];}delete [] matrix_data->Available;delete [] matrix_data->Allocation;delete [] matrix_data->Max;delete [] matrix_data->Need;}void Banker_alogrithm(int n, int m,int f, int *req ,struct MD *matrix_data){int i(0);int *Work = new int[m]; //工作向量bool *Finish = new bool[n]; //finish[*] 标识进程是否安全int *Order = new int[n]; //记录安全进程序列for(i = 0; i < n; i++){Finish[i] = false;Order[i] = 0;}if(Request_less_or_equal_need(m,f,req,matrix_data)){if(Request_less_or_equal_available(m,f,req,matrix_data)){Try_to_allocated_resources(m,f,req,matrix_data);if(Is_security_or_not(n,m,f,matrix_data,Work,Finish,Order)){cout<<"进程存在安全序列: ";for(i = 0; i < n; i++){cout<<"P"<<Order[i]<<" ";}cout<<", 系统己分配进程P"<<f<<"请求资源。"<<endl;}else{cout<<"系统进入不安全状态，不分配请求资源。"<<endl;Restore(m,f,req,matrix_data);}}else{cout<<"没有足够的资源可以分配, 进程P"<<f<<"需要等待, "; cout<<"资源请求向量request["<<m<<"]="; for(i = 0; i < m; i++) cout<<req[i]<<" "; cout<<"中某一项超过进程可利用资源Available["<<f<<"]["<<m<<"]="; for(i = 0; i < m; i++) cout<<matrix_data->Available[i]<<" "; cout<<endl;}}else{cout<<"数据错误。资源请求向量request["<<m<<"]=";for(i = 0; i < m; i++)cout<<req[i]<<" ";cout<<"中某一项超过进程所需资源Need["<<f<<"]["<<m<<"]=";for(i = 0; i < m; i++)cout<<matrix_data->Need[f][i]<<" ";cout<<endl;}// 释放分配的内存delete[] Work;delete[] Finish;delete[] Order;}