C/C++ Program for Priority Scheduling Algorithm

Here you will get a C and C++ program for need planning calculation.

What is Priority Scheduling Algorithm?

In need booking calculation each procedure has a need related with it and as each procedure

hits the line, it is put away independent on its need so process with higher need is managed first.

It ought to be noticed that equivalent need forms are booked in FCFS request.

To forestall high need forms from running inconclusively the scheduler may diminish

the need of the presently running procedure at each clock tick (i.e., at each clock interfere).

On the off chance that this activity makes its need dip under that of the following most elevated procedure, a procedure

switch happens. On the other hand, each procedure might be allowed the greatest time quantum that it is permitted to run.

At the point when this quantum is spent, the following most elevated need process is allowed to run.

Limitations

The issue happens when the working framework gives a specific assignment a low need, so it

sits in the line for a bigger measure of time, not being managed by the CPU. On the off chance that this procedure is something the client needs, there could

be a long pause, this procedure is known as “Starvation” or “Interminable Blocking”.

Solution

Many working frameworks utilize a strategy called “maturing”, in which a low need process gradually gains need after some

time as it sits in the line. Regardless of whether the need for the procedure is low, there is a surety of its execution.

C Program

#include<stdio.h>
 
int main()
{
    int bt[20],p[20],wt[20],tat[20],pr[20],i,j,n,total=0,pos,temp,avg_wt,avg_tat;
    printf("Enter Total Number of Process:");
    scanf("%d",&n);
 
    printf("\nEnter Burst Time and Priority\n");
    for(i=0;i<n;i++)
    {
        printf("\nP[%d]\n",i+1);
        printf("Burst Time:");
        scanf("%d",&bt[i]);
        printf("Priority:");
        scanf("%d",&pr[i]);
        p[i]=i+1;           //contains process number
    }
 
    //sorting burst time, priority and process number in ascending order using selection sort
    for(i=0;i<n;i++)
    {
        pos=i;
        for(j=i+1;j<n;j++)
        {
            if(pr[j]<pr[pos])
                pos=j;
        }
 
        temp=pr[i];
        pr[i]=pr[pos];
        pr[pos]=temp;
 
        temp=bt[i];
        bt[i]=bt[pos];
        bt[pos]=temp;
 
        temp=p[i];
        p[i]=p[pos];
        p[pos]=temp;
    }
 
    wt[0]=0;	//waiting time for first process is zero
 
    //calculate waiting time
    for(i=1;i<n;i++)
    {
        wt[i]=0;
        for(j=0;j<i;j++)
            wt[i]+=bt[j];
 
        total+=wt[i];
    }
 
    avg_wt=total/n;      //average waiting time
    total=0;
 
    printf("\nProcess\t    Burst Time    \tWaiting Time\tTurnaround Time");
    for(i=0;i<n;i++)
    {
        tat[i]=bt[i]+wt[i];     //calculate turnaround time
        total+=tat[i];
        printf("\nP[%d]\t\t  %d\t\t    %d\t\t\t%d",p[i],bt[i],wt[i],tat[i]);
    }
 
    avg_tat=total/n;     //average turnaround time
    printf("\n\nAverage Waiting Time=%d",avg_wt);
    printf("\nAverage Turnaround Time=%d\n",avg_tat);
 
	return 0;
}

C++ Program

#include<iostream>
 
using namespace std;
 
int main()
{
    int bt[20],p[20],wt[20],tat[20],pr[20],i,j,n,total=0,pos,temp,avg_wt,avg_tat;
    cout<<"Enter Total Number of Process:";
    cin>>n;
 
    cout<<"\nEnter Burst Time and Priority\n";
    for(i=0;i<n;i++)
    {
        cout<<"\nP["<<i+1<<"]\n";
        cout<<"Burst Time:";
        cin>>bt[i];
        cout<<"Priority:";
        cin>>pr[i];
        p[i]=i+1;           //contains process number
    }
 
    //sorting burst time, priority and process number in ascending order using selection sort
    for(i=0;i<n;i++)
    {
        pos=i;
        for(j=i+1;j<n;j++)
        {
            if(pr[j]<pr[pos])
                pos=j;
        }
 
        temp=pr[i];
        pr[i]=pr[pos];
        pr[pos]=temp;
 
        temp=bt[i];
        bt[i]=bt[pos];
        bt[pos]=temp;
 
        temp=p[i];
        p[i]=p[pos];
        p[pos]=temp;
    }
 
    wt[0]=0;            //waiting time for first process is zero
 
    //calculate waiting time
    for(i=1;i<n;i++)
    {
        wt[i]=0;
        for(j=0;j<i;j++)
            wt[i]+=bt[j];
 
        total+=wt[i];
    }
 
    avg_wt=total/n;      //average waiting time
    total=0;
 
    cout<<"\nProcess\t    Burst Time    \tWaiting Time\tTurnaround Time";
    for(i=0;i<n;i++)
    {
        tat[i]=bt[i]+wt[i];     //calculate turnaround time
        total+=tat[i];
        cout<<"\nP["<<p[i]<<"]\t\t  "<<bt[i]<<"\t\t    "<<wt[i]<<"\t\t\t"<<tat[i];
    }
 
    avg_tat=total/n;     //average turnaround time
    cout<<"\n\nAverage Waiting Time="<<avg_wt;
    cout<<"\nAverage Turnaround Time="<<avg_tat;
 
    return 0;
}

Output