C++ program to implement Priority CPU scheduling algorithm

C++ programs to implement both Preemptive and non-Preemptive Priority CPU scheduling algorithm.

C++ program to implement Non Preemptive Priority CPU scheduling algorithm without arrival time

#include<iostream>
#include<iomanip>
using namespace std;
class priority_alg
{
    int pr[10],id[10],exe[10];
    int n;
    void sort(int *f,int *mid,int *last);
public:
    void getdata();
    void display();
    void cal_wt_tt();
};
void priority_alg::getdata()
{
    cout<<"How many process to be entered : ";
    cin>>n;
    for(int i=0;i<n;i++)
    {
        cout<<"Enter execution time and priority of "<<i+1<<" process : ";
        cin>>exe[i]>>pr[i];
        id[i]=i+1;
    }
}
void priority_alg::display()
{
    cout<<endl<<"Process ID\tExecution time\tPriority "<<endl;
    for(int i=0;i<n;i++)
        cout<<setw(5)<<id[i]<<setw(15)<<exe[i]<<setw(15)<<pr[i]<<endl;
}
void priority_alg::sort(int *f,int *mid,int *last)
{
    int temp;
    for(int y=0;y<n-1;y++)
    {
        for(int z=0;z<n-1;z++)
            if(f[z]>f[z+1])
            {
                temp=f[z];
                f[z]=f[z+1];
                f[z+1]=temp;
                temp=mid[z];
                mid[z]=mid[z+1];
                mid[z+1]=temp;
                temp=last[z];
                last[z]=last[z+1];
                last[z+1]=temp;
            }
    }
}
void priority_alg::cal_wt_tt()
{
float avg=0,avtnt=0,wt=0,tnt=0;
    sort(pr,id,exe);
    cout<<"\nProcess id \tWaiting time \tTurn around time "<<endl;
    for(int i=0;i<n;i++)
    {
        tnt+=exe[i];
        avtnt+=tnt;
        avg+=wt;
        cout<<setw(5)<<id[i]<<setw(15)<<tnt<<setw(15)<<wt<<endl;
        wt+=exe[i];
    }
    avg=avg/(float)n;
    avtnt/=(float)n;
    cout<<"\nAverage Waiting time     : "<<avg;
    cout<<"\nAverage turn Around time : "<<avtnt<<endl;
}
int main()
{
priority_alg priority;
priority.getdata();
priority.display();
priority.cal_wt_tt();
    return 0;
}

OUTPUT

C++ program to implement Non Preemptive Priority CPU scheduling algorithm with arrival time

#include<iostream>
#include<iomanip>
using namespace std;
class priority_alg
{
    int pr[10],id[10],exe[10],ar[10];
    int n;
    void sort(int*,int*,int*,int *);
public:
    void getdata();
    void display();
    void cal_wt_tt();
};
void priority_alg::getdata()
{
    cout<<"How many process to be entered : ";
    cin>>n;
    for(int i=0;i<n;i++)
    {
        cout<<"Enter execution,arrival time and priority of "<<i+1<<" process : ";
        cin>>exe[i]>>ar[i]>>pr[i];
        id[i]=i+1;
    }
}
void priority_alg::display()
{
    cout<<endl<<"Process ID\tExecution time\tArrival Time \tPriority "<<endl;
    for(int i=0;i<n;i++)
        cout<<setw(5)<<id[i]<<setw(15)<<exe[i]<<setw(15)<<ar[i]<<setw(15)<<pr[i]<<endl;
}
void priority_alg::sort(int *f,int *mid,int *last,int *ll)
{
    int temp;
    for(int y=0;y<n-1;y++)
    {
        for(int z=0;z<n-1;z++)
            if(f[z]>f[z+1])
            {
                temp=f[z];
                f[z]=f[z+1];
                f[z+1]=temp;
                temp=mid[z];
                mid[z]=mid[z+1];
                mid[z+1]=temp;
                temp=last[z];
                last[z]=last[z+1];
                last[z+1]=temp;
                temp=ll[z];
                ll[z]=ll[z+1];
                ll[z+1]=temp;
            }
    }
}
void priority_alg::cal_wt_tt()
{
int flag=1;
int at=0,ind,wt,tnt,min,max=pr[0];
float avg=0,avtnt=0;
sort(ar,id,exe,pr);
at=ar[0];
sort(pr,id,exe,ar);
for(int i=1;i<n;i++)
   if(max<pr[i])
      max=pr[i];
    min=max+1;
cout<<"\nProcess ID \tWaiting time \tTurn Around time "<<endl;
while(flag)
{
        for(int i=0;i<n;i++)
        {
            if(at>=ar[i]&&min>pr[i]&&id[i]>0)
   {
       ind=i;
       min=pr[i];
   }
        }
        if(id[ind]==-1)
        {
            at++;
            continue;
        }
   wt=at-ar[ind];
   at+=exe[ind];
   avg+=wt;
   tnt=at-ar[ind];
   avtnt+=tnt;
   cout<<setw(5)<<id[ind]<<setw(15)<<wt<<setw(15)<<tnt<<endl;
   id[ind]=-1;
   min=max+1;
   flag=0;
   for(int k=0;k<n;k++)
            if(id[k]!=-1)
               flag=1;
    }
    avg=avg/(float)n;
    avtnt/=(float)n;
    cout<<"\nAverage Waiting time     : "<<avg;
    cout<<"\nAverage turn Around time : "<<avtnt<<endl;
}
int main()
{
priority_alg priority;
priority.getdata();
priority.display();
priority.cal_wt_tt();
    return 0;
}

OUTPUT

C++ program to implement Preemptive Priority CPU scheduling algorithm with arrival time

#include<iostream>
#include<iomanip>
using namespace std;
class priority_alg
{
    int pr[10],id[10],exe[10],ar[10];
    int n;
    void sort(int*,int*,int*,int *);
public:
    void getdata();
    void display();
    void cal_wt_tt();
};
void priority_alg::getdata()
{
    cout<<"How many process to be entered : ";
    cin>>n;
    for(int i=0;i<n;i++)
    {
        cout<<"Enter execution,arrival time and priority of "<<i+1<<" process : ";
        cin>>exe[i]>>ar[i]>>pr[i];
        id[i]=i+1;
    }
}
void priority_alg::display()
{
    cout<<endl<<"Process ID\tExecution time\tArrival Time \tPriority "<<endl;
    for(int i=0;i<n;i++)
        cout<<setw(5)<<id[i]<<setw(15)<<exe[i]<<setw(15)<<ar[i]<<setw(15)<<pr[i]<<endl;
}
void priority_alg::sort(int *f,int *mid,int *last,int *ll)
{
    int temp;
    for(int y=0;y<n-1;y++)
    {
        for(int z=0;z<n-1;z++)
            if(f[z]>f[z+1])
            {
                temp=f[z];
                f[z]=f[z+1];
                f[z+1]=temp;
                temp=mid[z];
                mid[z]=mid[z+1];
                mid[z+1]=temp;
                temp=last[z];
                last[z]=last[z+1];
                last[z+1]=temp;
                temp=ll[z];
                ll[z]=ll[z+1];
                ll[z+1]=temp;
            }
    }
}
void priority_alg::cal_wt_tt()
{
int flag=1;
int exe2[10],at=0,ind,wt,tnt,min,max=pr[0];
float avg=0,avtnt=0;
sort(ar,id,exe,pr);
at=ar[0];
sort(pr,id,exe,ar);
for(int i=0;i<n;i++)
{
   if(max<pr[i])
      max=pr[i];
        exe2[i]=exe[i];
}
    min=max+1;
cout<<"\nProcess ID \tWaiting time \tTurn Around time "<<endl;
while(flag)
{
        for(int i=0;i<n;i++)
        {
            if(at>=ar[i]&&min>pr[i]&&id[i]>0)
            {
                ind=i;
       min=exe[i];
   }
   }
        at++;
        exe[ind]--;
        min=max+1;
        if(exe[ind]==0)
        {
            wt=at-exe2[ind]-ar[ind];
   tnt=at-ar[ind];
   cout<<setw(5)<<id[ind]<<setw(15)<<wt<<setw(15)<<tnt<<endl;
   id[ind]=-1;
   avg+=wt;
   avtnt+=tnt;
        }
   flag=0;
   for(int k=0;k<n;k++)
            if(id[k]!=-1)
               flag=1;
    }
    avg=avg/(float)n;
    avtnt/=(float)n;
    cout<<"\nAverage Waiting time     : "<<avg;
    cout<<"\nAverage turn Around time : "<<avtnt<<endl;
}
int main()
{
priority_alg priority;
priority.getdata();
priority.display();
priority.cal_wt_tt();
        return 0;
}

OUTPUT

C++ program to implement Preemptive Priority CPU scheduling algorithm with Gantt chart

Following program uses BGI graphics and compiled it using TurboC/C++ 3.0 compiler.

#include<graphics.h>
#include<iomanip.h>
#include<conio.h>
#include<string.h>
class priority_alg
{
    int pr[10],id[10],exe[10],ar[10];
    int n,x,y;
    char d[20];
    void sort(int*,int*,int*,int *);
public:
    void getdata();
    void display();
    void cal_wt_tt();
    void int_to_ch(int);
    void chart(int,int);
};
void priority_alg::getdata()
{
    cout<<"How many process to be entered : ";
    cin>>n;
    for(int i=0;i<n;i++)
    {
cout<<"Enter execution,arrival time and priority of "<<i+1<<" process : ";
cin>>exe[i]>>ar[i]>>pr[i];
id[i]=i+1;
    }
}
void priority_alg::int_to_ch(int temp)
{
   int i;
   if(temp==0)
   {
      d[0]=48;
      d[1]=0;
      return;
   }
   for(i=0;temp!=0;i++)
    {
d[i]=temp%10+48;
temp/=10;
    }
    d[i]=0;
    strrev(d);
}
void priority_alg::chart(int id,int t)
{
    rectangle(x,y,x+30,y+30);
    if(id!=-1)
    {
       int_to_ch(id);
       outtextxy(x+12,y+12,d);
    }
    int_to_ch(t);
    if(t>=10)
       outtextxy(x+24,y+33,d);
    else
       outtextxy(x+30,y+33,d);
    x+=30;
    if(x+60>getmaxx())
    {
       y+=50;
       x=5;
       outtextxy(x,y+33,d);
    }
}
void priority_alg::display()
{
    int gdriver = DETECT, gmode;
    initgraph(&gdriver, &gmode, "");
    outtextxy(5,56,"Process ID    Execution time   Arrival Time   Priority ");
    x=5,y=66;
    for(int i=0;i<n;i++,y+=16)
    {
int_to_ch(i+1);
outtextxy(35,y,d);
int_to_ch(exe[i]);
outtextxy(150,y,d);
int_to_ch(ar[i]);
outtextxy(270,y,d);
int_to_ch(pr[i]);
outtextxy(385,y,d);
    }
}
void priority_alg::sort(int *f,int *mid,int *last,int *ll)
{
    int temp;
    for(int y=0;y<n-1;y++)
    {
for(int z=0;z<n-1;z++)
   if(f[z]>f[z+1])
   {
temp=f[z];
f[z]=f[z+1];
f[z+1]=temp;
temp=mid[z];
mid[z]=mid[z+1];
mid[z+1]=temp;
temp=last[z];
last[z]=last[z+1];
last[z+1]=temp;
temp=ll[z];
ll[z]=ll[z+1];
ll[z+1]=temp;
   }
    }
}
void priority_alg::cal_wt_tt()
{
    int exe2[10],flag=1,z=y+10,prev,pa,pfl=0;
    int at=0,ind,wt,tnt,min,max=pr[0];
    float avg=0,avtnt=0;
    sort(ar,id,exe,pr);
    at=ar[0];
    sort(pr,id,exe,ar);
    for(int i=0;i<n;i++)
    {
exe2[i]=exe[i];
if(max<pr[i])
  max=pr[i];
    }
    min=max+1;
    y+=(n+2)*16;
    outtextxy(x,y+10,"GANTT CHART");
    y=y+26;
    int_to_ch(at);
    outtextxy(x,y+33,d);
    outtextxy(x,z,"Process id    Waiting time    Turn around time ");
    z=z+16;
    while(flag)
    {
for(int i=0;i<n;i++)
{
   if(at>=ar[i]&&min>pr[i]&&id[i]>0)
   {
ind=i;
min=exe[i];
   }
}
at++;
exe[ind]--;
min=max+1;
if(prev!=id[ind]&&pfl)
   chart(prev,pa);
prev=id[ind];
pa=at;
pfl=1;
if(exe[ind]==0)
{
   wt=at-exe2[ind]-ar[ind];
   tnt=at-ar[ind];
   int_to_ch(id[ind]);
   outtextxy(35,z,d);
   int_to_ch(wt);
   outtextxy(150,z,d);
   int_to_ch(tnt);
   outtextxy(270,z,d);
   z+=16;
   id[ind]=-1;
   avg+=wt;
   avtnt+=tnt;
}
flag=0;
for(int k=0;k<n;k++)
   if(id[k]!=-1)
      flag=1;
if(flag==0)
  chart(prev,pa);
    }
    avg=avg/(float)n;
    avtnt/=(float)n;
    cout<<"\nAverage Waiting time     : "<<avg;
    cout<<"\nAverage turn Around time : "<<avtnt<<endl;
}
int main()
{
    priority_alg priority;
    priority.getdata();
    priority.display();
    priority.cal_wt_tt();
    getch();
    return 0;
}

OUTPUT