Write a program that will simulate non - preemptive process scheduling algorithm

Question

Write a program that will simulate non - preemptive process scheduling algorithms in C++:

FCFS(First Come First Serve).

SJN(Shortest Job Next)

Priority

Your program should input the information necessary for the calculation of average turnaround time including:

Time required for a job execution;

Arrival time;

Priority

Note: The information can vary for different algorithms.

The output of the program should include: starting and terminating time for each job, turnaround time for each job, average turnaround time.

Explanation / Answer

FCFS(First Come First Serve)

#include<iostream>

using namespace std;

int main()

{

char pn[10][10],t[10];

int arr[10],bur[10],star[10],finish[10],tat[10],wt[10],i,j,n,temp;

int totwt=0,tottat=0;

cout<<"Enter the number of processes:";

cin>>n;

for(i=0;i<n;i++)

{

cout<<"Enter the Process Name, Arrival Time & Burst Time:";

cin>>pn[i]>>arr[i]>>bur[i];

}

for(i=0;i<n;i++)

{

for(j=0;j<n;j++)

{

if(arr[i]<arr[j])

{

temp=arr[i];

arr[i]=arr[j];

arr[j]=temp;

temp=bur[i];

bur[i]=bur[j];

bur[j]=temp;

strcpy(t,pn[i]);

strcpy(pn[i],pn[j]);

strcpy(pn[j],t);

}

}

}

for(i=0;i<n;i++)

{

if(i==0)

star[i]=arr[i];

else

star[i]=finish[i-1];

wt[i]=star[i]-arr[i];

finish[i]=star[i]+bur[i];

tat[i]=finish[i]-arr[i];

}

cout<<" PName Arrtime Burtime WaitTime Starttime Turnaroundtime Finishtime";

for(i=0;i<n;i++)

{

cout<<pn[i]<<arr[i]<<bur[i]<<wt[i]<<star[i]<<tat[i]<<finish[i];

totwt+=wt[i];

tottat+=tat[i];

}

cout<<" Average Waiting time:"<<(float)totwt/n;

cout<<" Average Turn Around Time:"<<(float)tottat/n;

return 0;

}

SJN(Shortest Job Next)

#include<iostream>

using namespace std;

int main()

{

int et[20],at[10],n,i,j,temp,st[10],ft[10],wt[10],ta[10];

int totwt=0,totta=0;

float awt,ata;

char pn[10][10],t[10];

cout<<"Enter the number of process:";

cin>>n;

for(i=0;i<n;i++)

{

cout<<"Enter process name, arrival time & execution time:";

cin>>pn[i]>>at[i]>>et[i];

}

for(i=0;i<n;i++)

for(j=0;j<n;j++)

{

if(et[i]<et[j])

{

temp=at[i];

at[i]=at[j];

at[j]=temp;

temp=et[i];

et[i]=et[j];

et[j]=temp;

strcpy(t,pn[i]);

strcpy(pn[i],pn[j]);

strcpy(pn[j],t);

}

}

for(i=0;i<n;i++)

{

if(i==0)

st[i]=at[i];

else

st[i]=ft[i-1];

wt[i]=st[i]-at[i];

ft[i]=st[i]+et[i];

ta[i]=ft[i]-at[i];

totwt+=wt[i];

totta+=ta[i];

}

awt=(float)totwt/n;

ata=(float)totta/n;

cout<<" Pname arrivaltime executiontime waitingtime tatime";

for(i=0;i<n;i++)

cout<<pn[i]<<at[i]<<et[i]<<wt[i]<<ta[i];

cout<<" Average waiting time is:"<<awt;

cout<<" Average turnaroundtime is:"<<ata;

}

Priority

#include<iostream>

using namespace std;

int main()

{

int et[20],at[10],n,i,j,temp,p[10],st[10],ft[10],wt[10],ta[10];

int totwt=0,totta=0;

float awt,ata;

char pn[10][10],t[10];

cout<<"Enter the number of process:";

cin>>n;

for(i=0;i<n;i++)

{

cout<<"Enter process name,arrivaltime,execution time & priority:";

cin>>pn[i]>>at[i]>>et[i]>>p[i];

}

for(i=0;i<n;i++)

for(j=0;j<n;j++)

{

if(p[i]<p[j])

{

temp=p[i];

p[i]=p[j];

p[j]=temp;

temp=at[i];

at[i]=at[j];

at[j]=temp;

temp=et[i];

et[i]=et[j];

et[j]=temp;

strcpy(t,pn[i]);

strcpy(pn[i],pn[j]);

strcpy(pn[j],t);

}

}

for(i=0;i<n;i++)

{

if(i==0)

{

st[i]=at[i];

wt[i]=st[i]-at[i];

ft[i]=st[i]+et[i];

ta[i]=ft[i]-at[i];

}

else

{

st[i]=ft[i-1];

wt[i]=st[i]-at[i];

ft[i]=st[i]+et[i];

ta[i]=ft[i]-at[i];

}

totwt+=wt[i];

totta+=ta[i];

}

awt=(float)totwt/n;

ata=(float)totta/n;

cout<<" Pname arrivaltime executiontime priority waitingtime tatime";

for(i=0;i<n;i++)

cout<<pn[i]<<at[i]<<et[i]<<p[i]<<wt[i]<<ta[i];

cout<<" Average waiting time is:"<<awt;

cout<<" Average turnaroundtime is"<<ata;

getch();

}

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