Banker’s Algorithm in C

Here you will get program for banker’s algorithm in C.

The banker’s algorithm  which is also known as avoidance algorithm is a deadlock detection algorithm. It was developed by Edsger Dijkstra. It is designed to check the safe state whenever a resource is requested. It takes analogy of bank, where customer request to withdraw cash. Based on some data the cash is lent to the customer. The banker can’t give more cash than what the customer has requested for, and the total available cash.  As this algorithm uses bank analogy so named as banker’s algorithm

The basic data structures used to implement this algorithm are given below.

Let n be the total number of processes and m be the total number of resource types in the system.

Available: A vector of length m. It shows number of available resources of each type. If Available[i] = k, then k instances of resource R_i are available.

Max: An n×m matrix that contain maximum demand of each process. If Max[i,j] = k, then process P_i can request maximum k instances of resource type R_j.

Allocation: An n×m matrix that contain number of resources of each type currently allocated to each process. If Allocation[i,j] = k, then P_i is currently allocated k instances of resource type R_j.

Need: An n×m matrix that shows the remaining resource need of each process. If Need[i,j] = k, then process P_i may need k more instances of resource type R_j to complete the task.

Program for Banker’s Algorithm in C

#include <stdio.h>

int current[5][5], maximum_claim[5][5], available[5];
int allocation[5] = {0, 0, 0, 0, 0};
int maxres[5], running[5], safe = 0;
int counter = 0, i, j, exec, resources, processes, k = 1;

int main()
{
	printf("\nEnter number of processes: ");
    	scanf("%d", &processes);

    	for (i = 0; i < processes; i++) 
	{
        	running[i] = 1;
        	counter++;
    	}

    	printf("\nEnter number of resources: ");
    	scanf("%d", &resources);

    	printf("\nEnter Claim Vector:");
    	for (i = 0; i < resources; i++) 
	{ 
	        scanf("%d", &maxres[i]);
    	}

   	printf("\nEnter Allocated Resource Table:\n");
    	for (i = 0; i < processes; i++) 
	{
	        for(j = 0; j < resources; j++) 
		{
  			scanf("%d", &current[i][j]);
        	}
    	}

    	printf("\nEnter Maximum Claim Table:\n");
    	for (i = 0; i < processes; i++) 
	{
        	for(j = 0; j < resources; j++) 
		{
            		scanf("%d", &maximum_claim[i][j]);
        	}
    	}

	printf("\nThe Claim Vector is: ");
    	for (i = 0; i < resources; i++) 
	{
	        printf("\t%d", maxres[i]);
	}

    	printf("\nThe Allocated Resource Table:\n");
    	for (i = 0; i < processes; i++) 
	{
	        for (j = 0; j < resources; j++) 
		{
            		printf("\t%d", current[i][j]);
        	}
		printf("\n");
    	}

    	printf("\nThe Maximum Claim Table:\n");
    	for (i = 0; i < processes; i++) 
	{
        	for (j = 0; j < resources; j++) 
		{
		        printf("\t%d", maximum_claim[i][j]);
        	}
        	printf("\n");
    	}

    	for (i = 0; i < processes; i++) 
	{
        	for (j = 0; j < resources; j++) 
		{
            		allocation[j] += current[i][j];
        	}
    	}

    	printf("\nAllocated resources:");
    	for (i = 0; i < resources; i++) 
	{
        	printf("\t%d", allocation[i]);
    	}

    	for (i = 0; i < resources; i++) 
	{
	        available[i] = maxres[i] - allocation[i];
	}

    	printf("\nAvailable resources:");
    	for (i = 0; i < resources; i++) 
	{
        	printf("\t%d", available[i]);
    	}
    	printf("\n");

    	while (counter != 0) 
	{
        	safe = 0;
        	for (i = 0; i < processes; i++) 
		{
            		if (running[i]) 
			{
                		exec = 1;
                		for (j = 0; j < resources; j++) 
				{
                    			if (maximum_claim[i][j] - current[i][j] > available[j]) 
					{
                        			exec = 0;
                        			break;
                    			}
                		}
                		if (exec) 
				{
                    			printf("\nProcess%d is executing\n", i + 1);
                    			running[i] = 0;
                    			counter--;
                    			safe = 1;

                    			for (j = 0; j < resources; j++) 
					{
                        			available[j] += current[i][j];
                    			}
			                break;
                		}
            		}
        	}
        	if (!safe) 
		{
            		printf("\nThe processes are in unsafe state.\n");
            		break;
        	} 
		else 
		{
            		printf("\nThe process is in safe state");
            		printf("\nAvailable vector:");

            		for (i = 0; i < resources; i++) 
			{
                		printf("\t%d", available[i]);
            		}

		        printf("\n");
        	}
    	}
    	return 0;
}

If you found anything incorrect in above program for banker’s algorithm in C then comment below.

Source: https://en.wikipedia.org/wiki/Banker%27s_algorithm

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