main.cpp

一个很好用的银行家算法,可以试试,欢迎大家,有好的和我联系

#include "iostream.h"
#include "string.h"
#include "conio.h"
#include "stdio.h"
int const M = 3;
int const N = 5;
//程序所用到的存储结构如下：
int Available[M] = {3,3,2};
int Max[N][M] = {{7,5,3},{3,2,2},{9,0,2},{2,2,2},{4,3,3}};
int Allocation[N][M] = {{0,1,0},{2,0,0},{3,0,2},{2,1,1},{0,0,2}};
int Need[N][M] = {{7,4,3},{1,2,2},{6,0,0},{0,1,1},{4,3,1}};

//所用函数声明如下：
bool CheckSecurity();     //安全性检测
bool CheckFinish(bool *End,int size);         //检测Finish数组是否全为true
void InitFinish(bool *Finish,int size);       //初始化Finish数组
bool Compare(int *first,int *last,int size);   //数组比较函数
void OutSafeQueue(int *queue,int size);         //输出安全序列
void Allocate(int *Request,int size,int index);  //尝试分配资源
void Recycle(int *Request,int size,int index);   //回收已分配的资源
void OutResource();                               //输出资源表
void Banker_Request(int *Request,int size,int index);  //资源请求函数
void Test();                                         //测试函数
void Init_Work(int *work,int size);				     //复制Available到Work数组
void Assign_Work(int *work,int size,int index);			//重新修改Work数组

int main()
{ 
	OutResource();
/*	int Request0[M] = {0,2,0};
//	int Request0[M] = {0,1,0};
	int Request1[M] = {1,0,2};
	int Request4[M]={3,3,0};
	cout << "\t***************模拟银行家算法****************\n";
	
	cout << "Press any key to start...\n" << endl;
	getch();
	cout << "进程1正在申请资源...\nPress any key to see the result...\n" << endl;
	getch();
	Banker_Request(Request1,M,1);
	cout << "Press any key to continue...\n"<< endl;
	getch();
	cout << "进程4正在申请资源...\nPress any key to see the result...\n" << endl;
	Banker_Request(Request4,M,4);
	cout << "Press any key to continue...\n"<< endl;
	getch();
	cout << "进程0正在申请资源...\nPress any key to see the result...\n" << endl;
	getch();
	Banker_Request(Request0,M,0);*/
	int Request[M];
	int index;
	char ch;
	char nameofResource[] = {'A','B','C'};
	do
	{
		cout << "请输入申请资源的进程编号：";
		cin >> index;
		cout << "-----请输入要申请的资源数----\n" << endl;
		for(int i = 0;i < M;i++)
		{
			cout << "资源" << nameofResource[i] <<':';
			cin >> Request[i];
		}
		Banker_Request(Request,M,index);
		cout << "\n如想继续申请其他资源请输入'y',否则输入'n'" << endl;
		cin >> ch;
		if(ch == 'n')
		{
			cout << "程序运行结束!" << endl;
			break;
		}
	}while(ch == 'y');
	return 0;
}

bool CheckSecurity()
{
	int Work[M];
	bool Finish[N];
	int queue[N];
	int i,k = 0;
	InitFinish(Finish,N);
	Init_Work(Work,M);
	int flag = 0;
	while(CheckFinish(Finish,N) == false)
	{
		for(i = 0;i < N;i++)
		{
			if(Finish[i] == false && Compare(Need[i],Work,sizeof(Work)/sizeof(int)))
			{
				Assign_Work(Work,M,i);
				Finish[i] = true;
				queue[k++] = i;
				flag = 1;
				break;
			}
				
		}
		if(flag == 0)
			return false;
		flag = 0;
	}
	if(CheckFinish(Finish,N))
		{
			cout << "存在一个安全序列:" << endl;
			OutSafeQueue(queue,k);
		}
	else 
		cout << "不存在一个安全序列!" << endl;
	return true;
}
bool CheckFinish(bool *End,int size)
{
	int n = size;
	for(int i = 0;i < n;i++)
	{
		if(End[i] == false)
			break;
	}
	if(i < n)
		return false;
	else return true;
}
void InitFinish(bool *Finish,int size)
{
	int n = size;
	int i = 0;
	for(i = 0;i < n;i++)
	{
		Finish[i] = false;
	}
}
bool Compare(int *first,int *last,int size)
{
	int n = size;
	for(int i = 0;i < n;i++)
	{
		if(first[i] > last[i])
			break;
	}
	if(i < n)
		return false;
	else 
		return true;
}
void OutSafeQueue(int *queue,int size)
{
	int n = size;
	cout << "\t";
	cout << '{';
	for(int i = 0;i < n;i++)
	{
		cout << "P" << queue[i] ;
		if(i != n-1)
		{
			cout << ", ";
		}
	}
	cout << '}';
	cout << endl;
}
void Allocate(int *Request,int size,int index)
{
	int k = index;
	int n = size;
	int *Allocate,*need;
	Allocate = Allocation[k];
	need = Need[k];
	for(int i = 0;i < n;i++)
	{
		Available[i] -= Request[i];
		Allocate[i] += Request[i];
		need[i] -= Request[i];
	}
}
void Recycle(int *Request,int size,int index)
{
	int n = size;
	int k = index;
	int *Allocate,*need;
	Allocate = Allocation[k];
	need = Need[k];
	for(int i = 0;i < n;i++)
	{
		Available[i] += Request[i];
		Allocate[i] -= Request[i];
		need[i] += Request[i];
	}
}
void Banker_Request(int *Request,int size,int index)
{
	int n = size;
	int k = index;
	if(Compare(Request,Need[k],n))
		if(Compare(Request,Available,n))
		{
			Allocate(Request,n,k);
		}
		else
		{
			cout << "目前尚无足够资源!进程需等待。" << endl;
			return;
		}
	else
	{
		cout << "申请的资源数已超过它所宣布的最大值!" << endl;
		return;
	}
	if(!CheckSecurity())
	{
		Recycle(Request,n,k);
		cout << "此时刻不存在一个安全序列"<< endl;
	}
}
void Test()
{
	for(int i = 0;i < N;i++)
		for(int j = 0;j < M;j++)
		{
			cout << Allocation[i][j] << ' ';
		}
	cout << endl;
	for(i = 0;i < N;i++)
		for(int j = 0;j < M;j++)
			cout << Need[i][j] << ' ';
	cout << endl;
	for(i = 0;i < M;i++)
    	cout << Available[i] << " ";
	cout << endl;
}
void Init_Work(int *work,int size)
{
	int n = size;
	for(int i = 0;i < n;i++)
	{
		work[i] = Available[i];
	}
}
void Assign_Work(int *work,int size,int index)
{
	int i = index;
	int n = size;
	for(int j = 0;j < n;j++)
	{
		work[j] = work[j] + Allocation[i][j];
	}
}
void OutResource()
{
	cout << "此时刻资源情况如下：" << endl;
	cout << "\t" << "MAX" << "\t " << "ALLOCATION" << "\t " << "NEED" 
		<< "\t " << "AVAILABLE" << endl;
	
	for(int i = 0;i < N;i++)
	{   
		cout << "\t";
		for(int j = 0;j < M;j++)
		{
			cout << Max[i][j] << " ";
		}
		cout << "\t ";
		for(j = 0;j < M;j++)
		{
			cout << Allocation[i][j] << " ";
		}
		cout << "\t\t ";
		for(j = 0;j < M;j++)
		{
			cout << Need[i][j] << " ";
		}
		if(i == 0) 
		{
			cout << "\t ";
			for(int k = 0;k < M;k++)
				cout << Available[k] << " ";
		}
		cout << endl;
	}
}