C Program Bankers Algorithm Example

C Program Bankers Algorithm Example

How to write a C Program to Banker Algorithm Example in C Programming Language ?

The Banker's algorithm, sometimes referred to as the avoidance algorithm, is a resource allocation and deadlock avoidance algorithm developed by Edsger Dijkstra that tests for safety by simulating the allocation of predetermined maximum possible amounts of all resources, and then makes an "s-state" check to test for possible deadlock conditions for all other pending activities, before deciding whether allocation should be allowed to continue.
The algorithm was developed in the design process for the THE operating system and originally described (in Dutch) in EWD108 When a new process enters a system, it must declare the maximum number of instances of each resource type that it may ever claim; clearly, that number may not exceed the total number of resources in the system. Also, when a process gets all its requested resources it must return them in a finite amount of time.

Solution:
  1. #include<stdio.h>
  2. #include<string.h>
  3. #include<stdlib.h>
  4. int n,m,i,j;
  5. int all[10][10],max [10][10],need[10][10];
  6. int avail[10],work[10],req[10];
  7. struct process
  8. {
  9.  char name[10];
  10.  int flag;
  11. }p[10];
  12.  
  13. void input()
  14. {
  15.  printf("enter the total number of process \n");
  16.  scanf("%d",&n);
  17.  for(i=0;i<n;i++)
  18.  {
  19.   printf("name:");
  20.   scanf("%s",p[i].name);
  21.   }
  22.   printf(" enter the number of resouces \n");
  23.   scanf("%d",&m);
  24.   printf(" enter the allocation matrix \n");
  25.   for(i=0;i<n;++i)
  26.   {
  27.    for(j=0;j<m;++j)
  28.    scanf("%d",&all[i][j]);
  29.   }
  30.   printf(" enter max matrix \n");
  31.   for(i=0;i<n;++i)
  32.   {
  33.    for(j=0;j<m;++j)
  34.    scanf("%d",&max[i][j]);
  35.   }
  36.   printf(" need matrix \n");
  37.   for(i=0;i<n;++i)
  38.    {
  39.     for(j=0;j<m;++j)
  40.     {
  41.      need[i][j]=max[i][j]-all[i][j];
  42.      printf(" %d ",need[i][j]);
  43.       printf("\n");
  44.      }
  45.    }
  46.      printf("\n");
  47.      printf("enter avaliable resources \n");
  48.      for(i=0;i<m;i++)
  49.       scanf("%d",&avail[i]);
  50. }
  51. void safeseq()
  52. {
  53.   int sseq[10],ss=0,chk=0,chki=0,count=0;
  54.   for(j=0;j<m;++j)
  55.    work[j]=avail[j];
  56.    for(i=0;i<n;++i)
  57.     p[i].flag=0;
  58.     while(count!=5)
  59.     {
  60.      for(i=0;i<n;++i)
  61.      {
  62.       chk=0;
  63.       for(j=0;j<m;++j)
  64.       {
  65.        if(p[i].flag==0)
  66.        {
  67.         if(need[i][j]<=work[j]);
  68.         chk++;
  69.         }
  70.         if(chk==m)
  71.         {
  72.          for(j=0;j<m;j++)
  73.          {
  74.           work[j]=work[j]+all[i][j];
  75.           printf("%d",work[j]);
  76.           p[i].flag=1;
  77.          }
  78.         sseq[ss]=1;
  79.         ss++;
  80.         count++;
  81.       }
  82.      }
  83.     }
  84.    }
  85.   for(i=0;i<n;++i)
  86.   {
  87.    if(p[i].flag==1)
  88.    chki++;
  89.    }
  90.    if(chki>=n)
  91.    {
  92.     printf("system is in safe state \n");
  93.     for(i=0;i<n;++i)
  94.      printf(" %d ",sseq[i]);
  95.     }
  96.     else
  97.     printf("not safe \n");
  98. }
  99. void request()
  100. {
  101.  int pro;
  102.  printf(" enter the process number of request \n");
  103.  scanf("%d",&pro);
  104.  printf(" enetr the request array \n");
  105.  for(i=0;i<m;++i);
  106.  scanf("%d",&req[i]);  
  107.  for(j=0;j<m;j++)
  108.  {
  109.   if(req[j]<=need[pro][j])
  110.   {
  111.    if(req[j]<=avail[j])
  112.    {
  113.     avail[j]=avail[j]-req[j];
  114.     all[pro][j]=all[pro][j]+req[j];
  115.     need[pro][j]=need[pro][j]-req[j];
  116.     printf(" avail: %d",avail[j]);
  117.    }
  118.   printf("\t need : %d",need[pro][j]);
  119.  }
  120.   else
  121.   {
  122.    printf("process has some kirik \n");
  123.    exit(0);
  124.   }
  125.  }
  126. }
  127. void print()
  128. {
  129.  printf("max matrix \n");
  130.   for(i=0;i<n;++i)
  131.   {
  132.    for(j=0;j<m;++j)
  133.    printf(" %d ",max[i][j]);
  134.     printf("\n");
  135.    }
  136.    printf("allocation matrix \n");
  137.   for(i=0;i<n;++i)
  138.   {
  139.    for(j=0;j<m;++j)
  140.    printf(" %d ",all[i][j]);
  141.     printf("\n");
  142.    }
  143.    printf("need matrix \n");
  144.   for(i=0;i<n;++i)
  145.   {
  146.    for(j=0;j<m;++j)
  147.    printf(" %d ",need[i][j]);
  148.     printf("\n");
  149.    }
  150.   printf(" \n availiable ");
  151.   for(i=0;i<m;++i)
  152.   printf(" %d ",avail[i]);
  153. }
  154. int main()
  155. {
  156.  int ch;
  157.  do{
  158.  printf("\n menu");
  159.  printf(" 1.input ");
  160.  printf("\n 2.safe seq ");
  161.  printf(" \n 3. request ");
  162.  printf("\n 4.print");
  163.  printf("\n 5.exit");
  164.  printf("\n enter choice ");
  165.  scanf("%d",&ch);
  166.  switch(ch)
  167.  {
  168.   case 1: input();
  169.    break;
  170.   case 2: safeseq();
  171.    break;
  172.    case 3: request();
  173.    break;
  174.    case 4: print();
  175.     break;
  176.     case 5:break;
  177.   }
  178.   }while(ch!=5);
  179. return 0;
  180. }


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