banker.c

银行家算法银行家算法银行家算法银行家算法

#include<stdio.h>	/*调用头文件*/
#include<string.h>
#define PRINT "%-s%6d%3d%3d%6d%3d%3d%6d%3d%3d\n\n",P[i].Name,P[i].Max.A,P[i].Max.B,P[i].Max.C,P[i].Allocation.A,P[i].Allocation.B,P[i].Allocation.C,P[i].Need.A,P[i].Need.B,P[i].Need.C			/*宏定义格式输出*/
typedef struct   /*声明资源结构体*/
{
	int A;		/*资源种类*/
	int B;
	int C;
}RESOURCE;

typedef struct		/*声明进程结构体*/
{
	char Name[3];	/*进程名称*/
	RESOURCE Max;		/*所需资源总数*/
	RESOURCE Allocation;	/*即时分配资源数*/
	RESOURCE Need;		/*需要分配资源数*/
	int Con;		/*进程状态位*/
}PROCESS;

PROCESS P[5]=				/*定义进程并初始化*/
{
	{"P0",7,5,3,0,1,0,7,4,3,0},
	{"P1",3,2,2,2,0,0,1,2,2,0},
	{"P2",9,0,2,3,0,2,6,0,0,0},
	{"P3",2,2,2,2,1,1,0,1,1,0},
	{"P4",4,3,3,0,0,2,4,3,1,0}
};

RESOURCE Available={3,3,2};	/*声明即时可用资源并初始化*/

void request();		/*调用函数声明*/
int test();
void pay();
void print();

void main()		/*主函数*/
{
	int i,j,k,m=-1;
	printf("         Max      Allocation     Need        Available\n");		/*输出即时资源分配现状*/
	printf("       A  B  C     A  B  C     A  B  C     A:3  B:3  C:2\n\n");
	for(i=0;i<5;i++)
		printf(PRINT);
	request();			/*函数调用*/
	test();
	printf("The safe queue is:\n");
	for(j=0;j<4;j++)
	{
		k=test();
		pay(k);
		print(k);
	}
	k=test();
	pay(k);
	printf("%s\n\n",P[k].Name);
	getchar();
}



void request()	/*资源申请模块*/
{
	int a,b,c;
	int i;
	char w[5];
	do
	{
		printf("Please input the process(\"eg:P2\") you want to request:");	/*选择要申请的进程名称*/
		scanf("%s",w);
	}while(strcmp(w,"P0")!=0&&strcmp(w,"P1")!=0&&strcmp(w,"P2")!=0&&strcmp(w,"P3")!=0&&strcmp(w,"P4")!=0);/*若输入不合法则提示重新输入*/
	printf("Please input the resource A you want to request:");		/*输入要申请资源数目*/
	scanf("%d",&a);
	printf("Please input the resource B you want to request:");
	scanf("%d",&b);
	printf("Please input the resource C you want to request:");
	scanf("%d",&c);
	for(i=0;i<5;i++)		/*资源申请判断*/
	{
		if(strcmp(P[i].Name,w)==0)	/*按名称查询进程*/
		{
			if(a<=Available.A&&b<=Available.B&&c<=Available.C)	/*若符合分配条件，分配资源*/
				if(a<=P[i].Need.A&&b<=P[i].Need.B&&c<=P[i].Need.C)
				{
					P[i].Allocation.A=P[i].Allocation.A+a;
					P[i].Allocation.B=P[i].Allocation.B+b;
					P[i].Allocation.C=P[i].Allocation.C+c;
					Available.A=Available.A-a;
					Available.B=Available.B-b;
					Available.C=Available.C-c;
					P[i].Need.A=P[i].Need.A-a;			/*即时可用资源重赋值*/
					P[i].Need.B=P[i].Need.B-b;
					P[i].Need.C=P[i].Need.C-c;
					break;
				}
				else
				{
					printf("The process does not need so much resources!\n");
					exit();
				}
			else		/*不符合，跳出程序*/
			{
				printf("Cannot request the resource!\n");
				exit();
			}
		}
	}
	if(i==5)		/*若无此进程，跳出程序*/
	{
		printf("Cannot request the resource!\n");
		exit();
	}
}

int test()	/*资源分配测试模块*/
{
	int i;
	for(i=0;i<5;i++)
	{
		if((P[i].Need.A<=Available.A)&&(P[i].Need.B<=Available.B)&&(P[i].Need.C<=Available.C)&&(P[i].Con==0))/*若可分配资源且状态位为'0'，则分配资源，返回进程名称号*/
		{
			Available.A=Available.A-P[i].Need.A;
			Available.B=Available.B-P[i].Need.B;
			Available.C=Available.C-P[i].Need.C;
			P[i].Allocation.A=P[i].Allocation.A+P[i].Need.A;
			P[i].Allocation.B=P[i].Allocation.B+P[i].Need.B;
			P[i].Allocation.C=P[i].Allocation.C+P[i].Need.C;
			P[i].Need.A=0;
			P[i].Need.B=0;
			P[i].Need.C=0;
			return(i);
			break;
		}
	}
	printf("Cannot request the resource!\n");
	exit();
}

void pay(int i)			/*资源返还模块*/
{
	Available.A=P[i].Max.A+Available.A;		/*资源返还，即时资源重赋值*/
	Available.B=P[i].Max.B+Available.B;
	Available.C=P[i].Max.C+Available.C;
	P[i].Con=1;			/*返还后状态位标志成'1'*/
}

void print(int i)		/*资源分配结果输出模块*/
{
	printf("%s-->",P[i].Name);
}