First Come First Serve

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QUADCOREDELUX 0 Newbie Poster

17 Years Ago

I Have these Programming Project In School Using Visual Basic 2005 Express, we were assigned to do a First Come First Serve Simulator however it's just my Second Year in College and I'm No good in Programming cause I'm not majoring in IT.. Any one can help me on how to start?

.net:vb.net visual-basic

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Latest Post 13 Years Ago Latest Post by Reverend Jim

Dani AI

Generated 10 Months Ago

began with an FCFS simulator and later posted an SJF attempt that fails at runtime. 's advice to break the task into the smallest pieces is exactly the right approach. The notes below point out the most likely causes of the runtime errors and give a compact, correct non‑preemptive SJF pattern that is easier to test and maintain than manual ReDim/Preserve array juggling.

Common mistakes found in the posted code: wrong fields used when sorting and swapping (which corrupts the array and causes index errors); arrays like sjf/npp used before they are initialized; mixing 1‑based loop logic with VB.NET’s 0‑based arrays; and swapped formulas for turnaround/waiting time. Correct formulas are: TAT = CompletionTime - ArrivalTime, and WT = TAT - BurstTime. Also, Gantt logic gets fragile if the scheduler does not explicitly advance current time when the CPU is idle.

A robust approach: load inputs into a List(Of Job) with properties ID, AT, BT; keep a single currentTime and repeatedly pick from jobs with AT <= currentTime the job having the smallest BT (tie-break by AT then ID). If none are available, set currentTime to the next job arrival. For each selected job: Start = currentTime; Finish = Start + BT; FT/TAT/WT as above; mark done and set currentTime = Finish. Use LINQ (.OrderBy/.ThenBy) or List.Sort instead of hand-coded swaps — it eliminates most index bugs and makes testing straightforward.

A minimal VB.NET pattern to implement the loop (replace fragile arrays with this):

Class Job
    Public Property ID As Integer
    Public Property AT As Integer
    Public Property BT As Integer
    Public Property FT As Integer
    Public Property TAT As Integer
    Public Property WT As Integer
    Public Property Done As Boolean
End Class

Dim current = jobs.Min(Function(j) j.AT)
While jobs.Any(Function(j) Not j.Done)
    Dim avail = jobs.Where(Function(j) Not j.Done AndAlso j.AT <= current) _
                    .OrderBy(Function(j) j.BT).ThenBy(Function(j) j.AT).ToList()
    If avail.Count = 0 Then
        current = jobs.Where(Function(j) Not j.Done).Min(Function(j) j.AT)
        Continue While
    End If
    Dim sel = avail.First()
    sel.FT = current + sel.BT
    sel.TAT = sel.FT - sel.AT
    sel.WT = sel.TAT - sel.BT
    sel.Done = True
    current = sel.FT
End While

Test with small, hand‑calculated cases and log Start/Finish per job in a ListBox; that makes bugs obvious and keeps the GUI work separate from the scheduling logic.

All 8 Replies

rapture 134 Posting Whiz in Training

17 Years Ago

I would start with reading your textbook and then break your project down to the smallest piece you can figure out on your own and if you get stuck post back as to what your problem is.

Reverend Jim 6,681 Hi, I'm Jim, one of DaniWeb's moderators.

13 Years Ago

We appreciate your willingness to contribute but please check the dates on posts before you respond to them This thread is more than three years old and it is likely that the original poster (OP) no longer needs help with this issue. Reviving this thread pushes more recent threads further down the list. If you continue to revive old threads you may be hit with an infraction.

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chirayu 0 Newbie Poster · Answer 1 · 2009-02-17T04:01:37+00:00

can you be more specific and give details of ur college project? that would help.

QUADCOREDELUX 0 Newbie Poster · Answer 2 · 2009-02-17T09:22:27+00:00

I'm totally Screwed with these:'( I can show the Screen

It's somewhat like the uploaded Image

It calculates a Job Inputed and shows out an output

QUADCOREDELUX 0 Newbie Poster · Answer 3 · 2009-02-17T14:16:57+00:00

Sorry for the Second Post here's the exact Screen Sample

QUADCOREDELUX 0 Newbie Poster · Answer 4 · 2009-02-17T14:19:36+00:00

Sorry for the Second Post here's the exact Screen Sample

QUADCOREDELUX 0 Newbie Poster · Answer 5 · 2009-03-27T14:19:30+00:00

I Manage to do that FCFS Codes now My Next Problems is with the Shortest Job First

I Have these Code but at Runtime it's totally Screwed. anyone who can help me with Shortest Job First CPU Sceduling :

Public Class Form7

    Private j() As Label
    Private b() As NumericUpDown
    Private a() As NumericUpDown
    Private p() As NumericUpDown
    Private t() As TextBox
    Private w() As TextBox
    Private g() As TextBox
    Private job() As job
    Dim ans As Integer
    Dim i As Integer
    Dim num As Integer
    Dim r As Random
    Dim rbt As Integer
    Dim rat As Integer
    Dim rp As Integer
    Dim rq As Integer
    Dim type As String
    Dim tbt As Integer
    Dim cpuu As Double
    Dim ttat As Integer
    Dim twt As Integer
    Dim atat As Double
    Dim awt As Double
    Dim tp As Double
    Dim i2 As Integer
    Dim i3 As Integer
    Dim n As Integer
    Dim max As Integer
    Dim gant() As String
    Dim temp() As job
    Dim temp2() As job
    Dim sjf() As job
    Dim npp() As job
    Dim turn As Integer
    Dim et As Integer


    Private Sub ComboBox1_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ComboBox1.TextChanged

        GroupBox1.Controls.Clear()
        GroupBox2.Controls.Clear()
        GroupBox3.Controls.Clear()
        GroupBox4.Controls.Clear()
        GroupBox5.Controls.Clear()
        GroupBox6.Controls.Clear()
        GroupBox14.Controls.Clear()
        num = Val(ComboBox1.Text)

        For i = 1 To num
            ReDim Preserve j(i)
            j(i) = New Label
            j(i).Top = i * 28
            j(i).Text = "Job " & i
            GroupBox1.Controls.Add(j(i))

            ReDim Preserve b(i)
            b(i) = New NumericUpDown
            b(i).Top = i * 28
            b(i).Left = 7
            b(i).Width = 85
            b(i).TextAlign = HorizontalAlignment.Center
            GroupBox2.Controls.Add(b(i))

            ReDim Preserve a(i)
            a(i) = New NumericUpDown
            a(i).Top = i * 28
            a(i).Left = 12
            a(i).Width = 90
            a(i).TextAlign = HorizontalAlignment.Center
            GroupBox3.Controls.Add(a(i))

            ReDim Preserve p(i)
            p(i) = New NumericUpDown
            p(i).Top = i * 28
            p(i).Left = 6
            p(i).Width = 85
            p(i).TextAlign = HorizontalAlignment.Center
            GroupBox4.Controls.Add(p(i))

            ReDim Preserve t(i)
            t(i) = New TextBox
            t(i).Top = i * 28
            t(i).Left = 9
            t(i).Width = 55
            t(i).TextAlign = HorizontalAlignment.Center
            GroupBox5.Controls.Add(t(i))


            ReDim Preserve w(i)
            w(i) = New TextBox
            w(i).Top = i * 28
            w(i).Left = 9
            w(i).Width = 55
            w(i).TextAlign = HorizontalAlignment.Center
            GroupBox6.Controls.Add(w(i))


        Next
    End Sub


    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        r = New Random()
        num = Val(ComboBox1.Text)
        For i = 1 To num
            rbt = r.Next(1, 15)
            rat = r.Next(0, 10)
            rp = r.Next(1, 5)
            rq = r.Next(1, 7)
            b(i).Value = rbt
            a(i).Value = rat
            p(i).Value = rp
            NumericUpDown1.Value = rq
        Next
    End Sub


    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        ListBox1.Items.Clear()
        ListBox2.Items.Clear()
        ListBox3.Items.Clear()
        ListBox4.Items.Clear()
        ListBox5.Items.Clear()
        ListBox6.Items.Clear()
        TextBox1.Clear()
        TextBox21.Clear()
        TextBox22.Clear()
        TextBox23.Clear()
        TextBox24.Clear()
        GroupBox5.Visible = True
        GroupBox6.Visible = True
        GroupBox7.Visible = True
        GroupBox8.Visible = True

        GroupBox10.Visible = False
        GroupBox14.Controls.Clear()
        tbt = 0
        ttat = 0
        twt = 0
        num = Val(ComboBox1.Text)

        For i = 1 To num
            Dim bt = b(i).Value
            Dim at = a(i).Value
            Dim pr = p(i).Value
            Dim id = i
            Dim ft = 0
            Dim tat = 0
            Dim wt = 0
            Dim t = 0
            Dim bto = b(i).Value
            ReDim Preserve job(i)
            ReDim Preserve temp(i)
            ReDim Preserve temp2(i)
            temp(i) = New job(bt = 0, at = 0, pr = 0, id = 0, ft = 0, tat = 0, wt = 0, t = 0, bto = 0)
            job(i) = New job(bt, at, pr, id, ft, tat, wt, t, bto)
            ListBox1.Items.Add(a(i).Value)
        Next
        sortAT()

        For i = 1 To num
            ListBox2.Items.Add(job(i).getAT)
            ListBox3.Items.Add(job(i).getID)
        Next

        'SJF routine
        For i = 1 To num
            If i = 1 Then
                job(i).ft = job(i).getBT + job(i).getAT
            ElseIf job(i).getBT > job(i - 1).ft Then
                job(i).ft = job(i).getAT + job(i).getBT
            Else
                job(i).ft = job(i - 1).getFT + job(i).getAT
            End If
            ListBox4.Items.Add(job(i).ft)
            ListBox5.Items.Add(job(i).getAT)
        Next
        For i = 1 To num
            job(i).tat = job(i).ft - job(i).getBT
            t(job(i).getID).Text = job(i).tat
            job(i).wt = job(i).tat - job(i).getAT
            w(job(i).getID).Text = job(i).wt
        Next

        totBT()
        totTAT()
        totWT()
        aveTAT()
        aveWT()
        util()
        tru()
        TextBox23.Text = cpuu
        TextBox21.Text = atat
        TextBox24.Text = tp
        TextBox22.Text = awt

        'max slots in gant chart and turn of jobs to enter micro
        max = num
        turn = 1
        For i = 1 To num
            If i = 1 Then
                If job(i).getBT <> 0 Then
                    max = max + 1
                    job(i).t = turn + 1
                    turn = turn + 1
                Else
                    job(i).t = turn
                End If
            End If

            If i > 1 Then
                If job(i).getBT > job(i - 1).getAT Then
                    max = max + 1
                    job(i).t = turn + 1
                    turn = turn + 1
                Else
                    job(i).t = turn
                End If
            End If
            turn = turn + 1
            ListBox6.Items.Add(job(i).t)
        Next
        TextBox1.Text = max
        TextBox2.Text = turn - 1


        'gant chart
        GroupBox14.Visible = True
        For i2 = 1 To max
            ReDim Preserve g(i2)
            g(i2) = New TextBox
            g(i2).TextAlign = HorizontalAlignment.Center
            g(i2).Left = i2 * 40 - 30
            g(i2).Width = 40
            g(i2).Top = 20
            GroupBox14.Controls.Add(g(i2))
        Next

        For i2 = 1 To max
            For i = 1 To num
                If job(i).t = i2 Then
                    g(i2).Text = "Job " & job(i).getID
                End If
            Next
            If g(i2).Text = "" Then
                g(i2).Text = "Idle"
            End If
        Next


    End Sub

    Public Sub sortAT()
        For i2 = 1 To num
            For i = 1 To num - 1
                If job(i).getBT < job(i + 1).getAT Then
                    temp(i) = job(i)
                    job(i) = job(i + 1)
                    job(i - 1) = temp(i)
                End If
            Next
        Next
    End Sub

    Public Sub sortPR()
        For i2 = 1 To ListBox5.Items.Count()
            For i = 1 To ListBox5.Items.Count() - 1
                If (npp(i).getPR > npp(i + 1).getPR) Then
                    temp(i) = npp(i)
                    npp(i) = npp(i + 1)
                    npp(i + 1) = temp(i)
                End If
            Next
        Next
    End Sub
    Public Sub totBT()
        For i = 1 To num
            tbt = tbt + job(i).bto
        Next
    End Sub
    Public Sub totTAT()
        For i = 1 To num
            ttat = ttat + job(i).tat
        Next
    End Sub
    Public Sub util()
        cpuu = (tbt / job(num).ft) * 100
    End Sub
    Public Sub aveTAT()
        atat = ttat / num
    End Sub
    Public Sub tru()
        tp = (num / job(num).ft)
    End Sub
    Public Sub aveWT()
        awt = (twt / num)
    End Sub
    Public Sub totWT()
        For i = 1 To num
            twt = twt + job(i).wt
        Next
    End Sub
    Public Sub sortBT()
        For i2 = 1 To ListBox5.Items.Count()
            For i = 1 To ListBox5.Items.Count() - 1
                If (sjf(i).getAT > sjf(i + 1).getBT) Then
                    temp(i) = sjf(i)
                    sjf(i) = sjf(i + 1)
                    sjf(i + 1) = temp(i)
                End If
            Next
        Next
    End Sub

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        GroupBox1.Visible = True
        GroupBox2.Visible = True
        GroupBox3.Visible = True
        GroupBox4.Visible = False
        GroupBox5.Visible = False
        GroupBox6.Visible = False
        GroupBox7.Visible = False
        GroupBox8.Visible = False

        GroupBox10.Visible = False

        GroupBox13.Visible = False
        GroupBox14.Visible = False
    End Sub

    Private Sub GroupBox4_Enter(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles GroupBox4.Enter

    End Sub


    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        Me.Close()

    End Sub

    
End Class

pAnUwAy -1 Newbie Poster · Answer 6 · 2013-01-15T15:45:41+00:00

pAnUwAy -1 Newbie Poster

13 Years Ago

can i see the form of this program?

TnTinMN commented: do you really think that someone who has not visited the site in 3 yrs is going to respond? -1

First Come First Serve

Dani AI

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