FCFS.c

/*First in, first out (FIFO), also known as first come, first served (FCFS), is the simplest scheduling algorithm.
 FIFO simply queues processes in the order of the arrival Time they arrive in the ready queue.
 In this, the process the arrival Time comes first will be executed first and next process starts only after the previous gets fully executed.*/


//FCFS -nonpreemptive algorithm with different arrival time
   
#include<stdio.h>

void findWaitingTime(int processes[],int n,int burstTime[],int waitingTime[],int arrivalTime[])
{
    int serviceTime[n];
    serviceTime[0]=0;
    waitingTime[0]=0;

    for (int i = 1; i < n; i++)
    {
        serviceTime[i]=serviceTime[i-1]+burstTime[i-1];
        waitingTime[i]=serviceTime[i]-arrivalTime[i];
        
        if (waitingTime[i]<0)
        {
            waitingTime[i]=0;
        }   
    }
}

void findTurnAroundTime(int processes[],int n,int burstTime[],int waitingTime[],int turnAroundTime[])
{
    for(int i=0;i<n;i++)
        turnAroundTime[i]=burstTime[i]+waitingTime[i];
}


void findAvgTime(int processes[],int n,int burstTime[],int arrivalTime[])
{
    int waitingTime[n],turnAroundTime[n];

    findWaitingTime(processes,n,burstTime,waitingTime,arrivalTime);
    findTurnAroundTime(processes,n,burstTime,waitingTime,turnAroundTime);

    printf("\n-----------------------------------------------------------------------------------------");
    printf("\nProcesses  Burst Time    Arrival Time   Waiting Time  Turn-Around Time  Completion Time");
    printf("\n-----------------------------------------------------------------------------------------");
    int total_waitingTime=0,total_turnAroundTime=0;


    for (int i = 0; i < n; i++)
    {
        total_waitingTime=total_waitingTime+waitingTime[i];
        total_turnAroundTime=total_turnAroundTime+turnAroundTime[i];
        int compl_time=turnAroundTime[i]+arrivalTime[i];

        printf("\n%6d  %8d  %13d  %14d  %15d %15d",i,burstTime[i],arrivalTime[i],waitingTime[i],turnAroundTime[i],compl_time);
    }

    printf("\nAverage Waiting Time = %0.3f",(float)total_waitingTime/(float)n);
    printf("\nAverage Turn Around Time = %0.3f",(float)total_turnAroundTime/(float)n);
}

void main()
{
    int processes[20],n,burstTime[20],arrivalTime[20],i;

    printf("Enter the number of processes:");
    scanf("%d",&n);

    printf("\nEnter Burst Times(in ms) of Processes:");
    printf("\n\n");
    for (i = 0; i < n; i++)
    {
        printf("Process %d:",i+1);
        scanf("%d",&burstTime[i]);
    }

    printf("\nEnter Arrival Times(in ms) of Processes:");
    printf("\n\n");
    for (i = 0; i < n; i++)
    {
        printf("Process %d:",i+1);
        scanf("%d",&arrivalTime[i]);
    }

    findAvgTime(processes,n,burstTime,arrivalTime);
}