Round Robin Process Sheduling Algorithm and Example Source Code in C

Round robin is the most widely used process scheduling algorithm .The basic strategy for round robin scheduling is that if there are n process,each of the process will receive 1/n CPU Execution Time.Each process is allotted a  time quanta, for which its is executed.The incoming processes are kept in a ready list while another one is executing.If the time quanta allotted for a process is over,then that process is moved to ready and the next process in the ready list is executed for the allotted time quanta.The Complete Example Implementation Source Code in C of Round Robin Algorithm to schedule N Processes and to calculate the Execution,wait time and turn around time is given below.

 #include<stdio.h>  
 void main()  
 {  
  int n,i,k,x=0,s=0,r=0,q=0,x=0,a[30],e[30],t[30];  
  float m,p=0;  
  printf("Enter the number of process:");  
  scanf("%d",&n);  
  printf("Enter the execution time:");  
  for(i=0;i<n;i++)  
  {  
  scanf("%d",&a[i]);  
  e[i]=a[i];  
  }  
  printf("Enter the quanta:");  
  scanf("%d",&q);  
  printf("After round robin sheduling:");  
  for(i=0;i<n;i++)  
  {  
  if(x<a[i])  
  {  
   x=a[i];  
  }  
  }  
  k=x/q;  
  while(s<=k)  
  {   
  for(i=0;i<n;i++)  
  {  
   if(a[i]>0)  
   {  
   if(a[i]>q)  
   {  
   r=r+q;  
   a[i]=a[i]-q;  
   printf("P%d\t",i+1);  
   }  
  else  
  {  
   r=r+a[i];  
   a[i]=a[i]-q;  
   printf("P%d ",i+1);  
   t[i]=r;  
  }  
  }  
 }  
 s++;  
 }  
 printf("\nPROCESS EXECUTION TIME  WAIT TIME  TURN AROUND TIME\n");  
 for(i=0;i<n;i++)  
 {  
  printf(" %d \t\t %d\t\t %d\t\t %d\t\t \n",i,e[i],x,t[i]);  
  x=x+q;  
 }  
 m=x/n;  
 printf("Average waiting time=%f",m);  
 printf("Average turn around time=");  
 for(i=0;i<n;i++)  
 p=p+t[i];  
 p=p/n;  
 printf("%f",p);  
 }