Exercise tasks Learn programming Visual Basic (VB.net)



Lesson:

Arrays, Structures and Strings


Exercise:

Exercise tasks


Objetive:

Create a Visual Basic (VB.net) program that can store up to 2000 "to-do tasks". For each task, it must keep the following data:

• Date (a set of 3 data: day, month and year)
• Description of task
• Level of importance (1 to 10)
• Category

The program should allow the user the following operations:

1 - Add a new task (the date must "seem correct": day 1 to 31, month 1 to 12, year between 1000 and 3000).

2 - Show the tasks between two certain dates (day, month and year). If the user presses Enter without specifying date, it will be taken as "today". It must display the number of each record, the date (DD/ MM/YYYY), description, category and importance, all in the same line, separated with hyphens.

3 - Find tasks that contain a certain text (in description or category, not case sensitive). It will display number, date and description (only 50 letters, in case it was be longer). The user should be notified if none is found.

4 - Update a record (it will ask for the number, will display the previous value of each field and the user can press Enter not to modify any of the data). The user should be warned (but not asked again) if he enters an incorrect record number. It is not necessary to validate any of the fields.

5 - Delete some data, between two positions indicated by the user. The user should be warned (but not asked again) if he enters any incorrect record number. Each record to be deleted must be displayed, and the user must be asked for confirmation.

6 - Sort the data alphabetically by date and (if two dates are the same) by description.

7 - Find Duplicates: If two records have the same description, both will be displayed on-screen.

Q - Quit (end the application; as we do not store the information, it will be lost).

(Hint: you can know the current date using DateTime.Now.Day, DateTime.Now.Month and DateTime.Now.Year).


Code:

Imports System
Public Class exercis95
    Structure DateType
        Public year As UShort
        Public month As Byte
        Public day As Byte
    End Structure

    Structure TaskType
        Public date As DateType
        Public description As String
        Public level As Byte
        Public category As String
    End Structure

    Public Shared Sub Main()
        Dim capacity As Integer = 2000
        Dim tasks As TaskType() = New TaskType(capacity - 1) {}
        Dim [option] As Char
        Dim counter As Integer = 0
        Dim search, newValue As String
        Dim found As Boolean

        Do
            Console.WriteLine()
            Console.WriteLine("Tasks database")
            Console.WriteLine()
            Console.WriteLine("1- Add a new task.")
            Console.WriteLine("2- Show the tasks between two certain dates.")
            Console.WriteLine("3- Find tasks that contain a certain text.")
            Console.WriteLine("4- Update a record.")
            Console.WriteLine("5- Delete some data, between two positions indicated.")
            Console.WriteLine("6- Sort the data alphabetically by date.")
            Console.WriteLine("7- Find Duplicates.")
            Console.WriteLine("Q- Quit.")
            Console.WriteLine("Enter an option:")
            [option] = Convert.ToChar(Console.ReadLine().ToUpper())

            Select Case [option]
                Case "1"c

                    If counter < capacity Then
                        Console.Write("Enter the Description of the task: ")
                        tasks(counter).description = Console.ReadLine()
                        Console.Write("Enter the Level of the task (1-10): ")
                        tasks(counter).level = Convert.ToByte(Console.ReadLine())
                        Console.Write("Enter the Category of the task: ")
                        tasks(counter).category = Console.ReadLine()

                        Do
                            Console.Write("Enter the Day of the task (1 to 31): ")
                            tasks(counter).date.day = Convert.ToByte(Console.ReadLine())
                            If tasks(counter).date.day < 1 OrElse tasks(counter).date.day > 31 Then Console.WriteLine("Not a valid day!")
                        Loop While tasks(counter).date.day < 1 OrElse tasks(counter).date.day > 31

                        Do
                            Console.Write("Enter the Month of the task (1 to 12): ")
                            tasks(counter).date.month = Convert.ToByte(Console.ReadLine())
                            If tasks(counter).date.month < 1 OrElse tasks(counter).date.month > 12 Then Console.WriteLine("Not a valid month!")
                        Loop While tasks(counter).date.month < 1 OrElse tasks(counter).date.month > 12

                        Do
                            Console.Write("Enter the Year of the task: ")
                            tasks(counter).date.year = Convert.ToUInt16(Console.ReadLine())
                            If tasks(counter).date.year < 1000 OrElse tasks(counter).date.year > 3000 Then Console.WriteLine("Not a valid year!")
                        Loop While tasks(counter).date.year < 1000 OrElse tasks(counter).date.year > 3000

                        counter += 1
                    Else
                        Console.WriteLine("Database full.")
                    End If

                Case "2"c

                    If counter >= 1 Then
                        Dim startDay, startMonth As Byte
                        Dim startYear As UShort
                        Dim endDay, endMonth As Byte
                        Dim endYear As UShort
                        Console.WriteLine("Starting day: ")
                        Dim number As String = Console.ReadLine()

                        If number = "" Then
                            startDay = Convert.ToByte(DateTime.Now.Day)
                        Else
                            startDay = Convert.ToByte(number)
                        End If

                        Console.WriteLine("Starting month: ")
                        number = Console.ReadLine()

                        If number = "" Then
                            startMonth = Convert.ToByte(DateTime.Now.Month)
                        Else
                            startMonth = Convert.ToByte(number)
                        End If

                        Console.WriteLine("Starting year: ")
                        number = Console.ReadLine()

                        If number = "" Then
                            startYear = Convert.ToUInt16(DateTime.Now.Year)
                        Else
                            startYear = Convert.ToUInt16(number)
                        End If

                        Console.WriteLine("Final day: ")
                        number = Console.ReadLine()

                        If number = "" Then
                            endDay = Convert.ToByte(DateTime.Now.Day)
                        Else
                            endDay = Convert.ToByte(number)
                        End If

                        Console.WriteLine("Final month: ")
                        number = Console.ReadLine()

                        If number = "" Then
                            endMonth = Convert.ToByte(DateTime.Now.Month)
                        Else
                            endMonth = Convert.ToByte(number)
                        End If

                        Console.WriteLine("Final year: ")
                        number = Console.ReadLine()

                        If number = "" Then
                            endYear = Convert.ToUInt16(DateTime.Now.Year)
                        Else
                            endYear = Convert.ToUInt16(number)
                        End If

                        Dim startDate As String = "" & startYear & startMonth.ToString("00") & startDay.ToString("00")
                        Dim endDate As String = "" & endYear & endMonth.ToString("00") & endDay.ToString("00")

                        For i As Integer = 0 To counter - 1
                            Dim currentDate As String = "" & tasks(i).date.year & tasks(i).date.month.ToString("00") & tasks(i).date.day.ToString("00")

                            If currentDate.CompareTo(startDate) >= 0 AndAlso currentDate.CompareTo(endDate) <= 0 Then
                                Console.WriteLine("The number is {0}: {1}/{2}/" & "{3} - {4} - {5} - {6}.", i + 1, tasks(i).date.day, tasks(i).date.month, tasks(i).date.year, tasks(i).description, tasks(i).category, tasks(i).level)
                            End If
                        Next
                    Else
                        Console.WriteLine("Database empty.")
                    End If

                Case "3"c

                    If counter >= 1 Then
                        Console.Write("Enter the text to search: ")
                        search = Console.ReadLine()
                        found = False
                        Dim newValue5 As String

                        For i As Integer = 0 To counter - 1

                            If tasks(i).description.IndexOf(search) >= 0 OrElse tasks(i).category.IndexOf(search) >= 0 Then

                                If tasks(i).description.Length > 50 Then
                                    newValue5 = tasks(i).description.Substring(0, 50)
                                Else
                                    newValue5 = tasks(i).description
                                End If

                                found = True
                                Console.WriteLine("{0}: {1}/{2}/{3} - {4}", i + 1, tasks(i).date.day, tasks(i).date.month, tasks(i).date.year, newValue5)
                            End If
                        Next

                        If Not found Then Console.WriteLine("Not found.")
                    Else
                        Console.WriteLine("Database empty.")
                    End If

                Case "4"c

                    If counter >= 1 Then
                        Console.Write("Enter the number of the task to update: ")
                        Dim update As Integer = Convert.ToInt32(Console.ReadLine()) - 1

                        If (update >= 0) AndAlso (update < counter) Then
                            Console.Write("Description ({0}): ", tasks(update).description)
                            newValue = Console.ReadLine()
                            If newValue <> "" Then tasks(update).description = newValue
                            Console.WriteLine("Level ({0}): ", tasks(update).level)
                            newValue = Console.ReadLine()
                            If newValue <> "" Then tasks(update).level = Convert.ToByte(newValue)
                            Console.WriteLine("Category ({0}): ", tasks(update).category)
                            newValue = Console.ReadLine()
                            If newValue <> "" Then tasks(update).category = newValue
                            Console.WriteLine("Year ({0}): ", tasks(update).date.year)
                            newValue = Console.ReadLine()
                            If newValue <> "" Then tasks(update).date.year = Convert.ToUInt16(newValue)
                            Console.WriteLine("Month ({0}): ", tasks(update).date.month)
                            newValue = Console.ReadLine()
                            If newValue <> "" Then tasks(update).date.month = Convert.ToByte(newValue)
                            Console.WriteLine("Day ({0}): ", tasks(update).date.day)
                            newValue = Console.ReadLine()
                            If newValue <> "" Then tasks(update).date.day = Convert.ToByte(newValue)
                        Else
                            Console.WriteLine("Wrong number entered.")
                        End If
                    Else
                        Console.WriteLine("Database empty.")
                    End If

                Case "5"c

                    If counter >= 1 Then
                        Console.Write("Enter the first number of data to delete: ")
                        Dim delete As Integer = Convert.ToInt32(Console.ReadLine()) - 1
                        Console.Write("Enter the second number of data to delete: ")
                        Dim delete2 As Integer = Convert.ToInt32(Console.ReadLine()) - 1

                        For pos As Integer = delete To delete2

                            For i As Integer = delete To counter - 1
                                tasks(i) = tasks(i + 1)
                            Next

                            counter -= 1
                        Next
                    Else
                        Console.WriteLine("Database empty.")
                    End If

                Case "6"c

                    For i As Integer = 0 To counter - 1 - 1
                        Dim firstDate As String = "" & tasks(i).date.year & tasks(i).date.month.ToString("00") & tasks(i).date.day.ToString("00") & tasks(i).description

                        For j As Integer = i + 1 To counter - 1
                            Dim secondDate As String = "" & tasks(j).date.year & tasks(j).date.month.ToString("00") & tasks(j).date.day.ToString("00") & tasks(j).description

                            If firstDate.CompareTo(secondDate) > 0 Then
                                Dim aux As TaskType = tasks(i)
                                tasks(i) = tasks(j)
                                tasks(j) = aux
                            End If
                        Next
                    Next

                Case "7"c

                    For i As Integer = 0 To counter - 1 - 1

                        For j As Integer = i + 1 To counter - 1

                            If tasks(i).description = tasks(j).description Then
                                Console.WriteLine("{0} - {1}/{2}/{3}", tasks(i).description, tasks(i).date.day, tasks(i).date.month, tasks(i).date.year)
                                Console.WriteLine("{0} - {1}/{2}/{3}", tasks(j).description, tasks(j).date.day, tasks(j).date.month, tasks(j).date.year)
                            End If
                        Next
                    Next

                Case "Q"c
                    Console.WriteLine("Quitting...")
                Case Else
                    Console.WriteLine("You entered a wrong option. Please re-enter it.")
            End Select
        Loop While [option] <> "Q"c
    End Sub
End Class



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