exam5te.c

用C写的银行家算法……在学操作系统的朋友可以参考一下

#include "dos.h" 
#include "conio.h" 
#include "alloc.h" 

int available[10]={3,3,2,3,3,2,3,3,2,5};
int max[6][10]={{7,5,3,3,2,2,3,2,2,1},{3,2,2,3,2,2,3,2,2,1},{9,2,0,2,3,2,2,3,2,1},{2,2,2,3,2,2,3,2,2,1},{4,3,3,3,2,2,3,2,2,1}};
int allocation[6][10]={{0,1,0,0,1,0,0,1,0,1},{2,0,0,0,1,0,0,1,0,1},{3,0,2,2,0,0,0,1,0,0},{2,1,1,3,0,2,2,0,0,0},{0,0,2,2,1,1,3,0,2,2}};
int need[6][10]={{7,4,3,3,2,2,3,2,2,1},{1,2,2,3,2,2,3,2,2,1},{6,0,0,3,2,2,3,2,2,1},{0,1,1,2,0,2,3,2,2,3},{4,3,1,2,0,2,3,2,2,3}};
int alive[5]={1,1,1,1,1};
int stay[3][3]; 
int request[10],process[5];
int i,j,p=5,pro,x,k1; 
void label()
{ x=1; 
printf("\n             Max             Allocation            Need             Available\n");
printf("PRO A B C D E F G H I J A B C D E F G H I J A B C D E F G H I J A B C D E F G H I J\n");
for(i=0;i<p;i++) 
{ if(alive[i]==1)
{ printf("P%d ",i); 
for(j=0;j<=9;j++)
{printf("%-3d",max[i][j]);}printf(" "); 
for(j=0;j<=9;j++)
{printf("%-3d",allocation[i][j]);}printf(" "); 
for(j=0;j<=9;j++)
{printf("%-3d",need[i][j]);}printf(" "); 
} 
if(x==1&&alive[i]==1) {printf("%-3d%-3d%-3d%-3d%-3d%-3d%-3d%-3d%-3d%-3d",available[0],available[1],available[2],available[3],available[4],available[5],available[6],available[7],available[8],available[9]);x=0;}
if(alive[i]==1) printf("\n");
} 
} 
int go()
{ int v=1; 
for(i=0;i<=9;i++)
{if(need[pro][i]<request[i]) {v=0;break;} 
if(available[i]<request[i]) {v=0;break;}} 
if(v==1){for(i=0;i<=9;i++)
{stay[0][i]=allocation[pro][i];allocation[pro][i]+=request[i]; 
stay[1][i]=need[pro][i];need[pro][i]-=request[i]; 
stay[2][i]=available[i];available[i]-=request[i];} 
} 
return(v); 
} 
int test() 
{ int work[10],finish[5]={0,0,0,0,0},v,k=0,t=0;
for(i=0;i<p;i++) 
if(alive[i]==0) {finish[i]=1;k1--;}
for(i=0;i<=9;i++) work[i]=available[i];
while(1) 
{ for(i=0;i<=4;i++) 
{ if(finish[i]==0) { v=1; 
for(j=0;j<=9;j++)
if(need[i][j]>work[j]) {v=0;break;} 
if(v==1) { finish[i]=1; 
for(j=0;j<=9;j++) work[j]+=allocation[i][j];
process[k]=i;k++; 
} 
} 
} 
if(t==k) break; 
else t=k; 
if(k==k1) break; 
} 
if(k==k1) return(1); 
else return(0); 

} 
main() 
{ 
while(1) 
{label();
k1=5; 
printf("Please choose one process(0,1,2,3,4):P");
scanf("%d",&pro); 
if(pro<0||pro>4) break; 
printf("The ten numbers of P%d's requests(,):",pro);
scanf("%d,%d,%d,%d,%d,%d,%d,%d,%d,%d",&request[0],&request[1],&request[2],&request[3],&request[4],&request[5],&request[6],&request[7],&request[8],&request[9]);
if(go()==0) {printf("Error\n",pro);
printf("Press any key to continue...");}
else if(test()==0) {printf("The system is not safe!\n",pro);
for(i=0;i<=9;i++)
{ allocation[pro][i]=stay[0][i]; 
need[pro][i]=stay[1][i]; 
available[i]=stay[2][i];} 
printf("Press any key to continue...");}
else {label();printf("The system is now safe!\n");
printf("The sequenceof safety:");
for(i=0;i<k1-1;i++) 
printf("P%d>",process[i]); 
printf("P%d",process[k1-1]); 
printf("\n Press any key to continue...");}
if(need[pro][0]==0&&need[pro][1]==0&&need[pro][2]==0&&need[pro][3]==0&&need[pro][4]==0&&need[pro][5]==0&&need[pro][6]==0&&need[pro][7]==0&&need[pro][8]==0&&need[pro][9]==0)
for(i=0;i<=9;i++)
{available[i]+=max[pro][i]; 
alive[pro]=0;}
getch(); 

delay(5000); 
} 
}