OS Project - First Come First Served

fcfs.c

#include <stdio.h>

// Coded by Raven G. Duran

struct process {
  int arrival_time;
  int burst_time;
  int waiting_time;
  int turnaround_time;

  int start_time;
  int end_time;
};

int main(int argc, const char *argv[]){
  int n,i,j;
  float average_burst = 0, average_waiting = 0, average_turnaround = 0;
  struct process p[20];

  printf("--- First come first served ---\n");
  printf("Number of processes: ");
  scanf("%d",&n);

  for (i = 0; i < n; i++) {
    printf("\n::Process %d::\n",i+1);
    printf("Arrival time: ");
    scanf("%d",&p[i].arrival_time);
    printf("Burst time: ");
    scanf("%d",&p[i].burst_time);
  }

  // Simulate the processes and calculate for each attribute
  for (i = 0; i < n; i++){
    if (i == 0) { // Special case set for the first process
      p[i].start_time = p[i].arrival_time;
      p[i].end_time = p[i].arrival_time + p[i].burst_time;
      p[i].waiting_time = 0;
      p[i].turnaround_time = p[i].burst_time;
    } else { // Non first processes
      p[i].start_time = p[i-1].end_time;
      p[i].end_time = p[i].start_time + p[i].burst_time;
      p[i].waiting_time = (p[i-1].start_time + p[i-1].burst_time) - p[i].arrival_time;
      p[i].turnaround_time = p[i].burst_time + p[i].waiting_time;
    }

    average_burst += (float) p[i].burst_time;
    average_waiting += (float) p[i].waiting_time;
    average_turnaround += (float) p[i].turnaround_time;
  }

  // Calculate average
  average_burst /= (float)n;
  average_waiting /= (float)n;
  average_turnaround /= (float)n;

  printf("\n\n----- Results -----\n\n");
  //printf("P%d  :  Arrived at %d : Bursted for %d\n",i+1,p[i].arrival_time,p[i].burst_time);
  printf("%-9s %-3s %-12s %-3s %-10s %-3s %-12s %-3s %-15s\n","Processes"," ","Arrival time"," ","Burst time"," ","Waiting time"," ","Turnaround time");
  for (i = 0; i < n; i++){
    printf("P%-8d %-3s %-12d %-3s %-10d %-3s %-12d %-3s %-15d\n",i+1," ",p[i].arrival_time," ",p[i].burst_time," ",p[i].waiting_time," ",p[i].turnaround_time);
    for (j = 1; j <= 78; j++) printf("-"); // Prints a line
    printf("\n");
  }

  printf("\n\n");
  printf("%-9s %-3s %-12s %-3s %-10.2f %-3s %-12.2f %-3s %-15.2f\n","Average"," ","-"," ",average_burst," ",average_waiting," ",average_turnaround);
  for (j = 1; j <= 78; j++) printf("-"); // Prints a line
  printf("\n");

  return 0;
}