Data Reading and Formatting

Data Reading

Introduction

The Console class uses Write() or WriteLine() to display values in the DOS window. As opposed to displaying something on the screen, you may want to request a value from the user. To support this, the Console class provides the Read() method.

To use it, the name of a variable can be assigned to it. The syntax used is:

VariableName = Console.Read()

When the user types something and presses Enter, what the user had typed would be assigned to the variable specified on the left side of the assignment operator.

Read() doesn't always have to assign its value to a variable. For example, it can be used on its own line, which simply means that the user is expected to type something but the value typed by the user would not be used for any significant purpose. For example, you can use the Read() function to wait for the user to press any key in order to close the DOS window.

Besides Read(), the Console class also provides ReadLine(). Like WriteLine(), after performing its assignment, ReadLine() sends the caret to the next line. Otherwise, it plays the same role as the Read() function.

Practical LearningPractical Learning: Introducing Data Reading

  1. Start Microsoft Visual Studio
  2. Create a new Console Application named GCS1
  3. In the Solution Explorer, right-click Module1 and click Rename
  4. Type OrderProcessing.vb and press Enter.
    If asked whether you want to rename the file, click Yes
  5. In the Code Editor, change the file as follows:
    Module OrderProcessing

    Sub  Main() 

        
    End Sub

End Module
  6. Save the file

String Value Request

In most assignments of your programs, you will not know the value of a string when writing your application. For example, you may want the user to provide such a string. To request a string (or any of the variables we will see in this lesson), you can call the Console.Read() or the Console.ReadLine() function and assign it to the name of the variable whose value you want to retrieve. Here is an example:

Module Module1

    Sub Main()
        Dim FirstName As String
        Console.Write("Enter First Name: ")
        FirstName = Console.ReadLine()
    End Sub

End Module

Practical LearningPractical Learning: Reading String Values

  1. To request strings from the user, change the file as follows: 
    Module OrderProcessing

    Sub Main() 
        Dim CustomerName As String
        Dim HomePhone As String

        Console.WriteLine("-/- Georgetown Cleaning Services -/-")
        ' Request customer information from the user
        Console.Write("Enter Customer Name:  ")
        CustomerName = Console.ReadLine()
        Console.Write("Enter Customer Phone: ")
        HomePhone = Console.ReadLine()

        Console.WriteLine()
        ' Display the receipt
        Console.WriteLine("====================================")
        Console.WriteLine("-/- Georgetown Cleaning Services -/-")
        Console.WriteLine("====================================")
        Console.WriteLine("Customer:   " + CustomerName)
        Console.WriteLine("Home Phone: " + HomePhone)
        Console.WriteLine("====================================")
    End Sub

End Module
  2. To execute the program, press Ctrl + F5
  3. Enter the customer name as James Watson
  4. Enter the phone number as (410) 493-2005
    This would produce: 
    -/- Georgetown Cleaning Services -/-
Enter Customer Name:  James Watson
Enter Customer Phone: (410) 493-2005

====================================
-/- Georgetown Cleaning Services -/-
====================================
Customer:   James Watson
Home Phone: (410) 493-2005
====================================
  5. Return to your programming environment

Number Request

Everything the user types is a string. If you want to get a number from the user, first request a string. Here is an example:

Module Module1

    Sub Main()
        Dim Number As Integer
        Dim strNumber As String

        Console.Write("Enter a natural number: ")
        strNumber = Console.ReadLine()
    End Sub

End Module

After getting the string, you must convert it to a number. To perform this conversion, you can use one of the conversion functions we mentioned in Lesson 2 for each data type. Here is an example:

Module Module1

    Sub Main()
        Dim Number As Integer
        Dim dblNumber As Integer
        Dim strNumber As String

        Console.Write("Enter a natural number: ")
        strNumber = Console.ReadLine()
        Number = CInt(strNumber)

        dblNumber = Number * 2
        Console.WriteLine("Number: " + CStr(dblNumber))
    End Sub

End Module

An advanced but faster way to do this is to type Console.ReadLine() in the parentheses of the conversion function. This has the same effect. Here is an example:

Module Module1

    Sub Main()
        Dim Number As Integer
        Dim dblNumber As Integer

        Console.Write("Enter a natural number: ")
        Number = CInt(Console.ReadLine())

        dblNumber = Number * 2
        Console.WriteLine("Number: " + CStr(dblNumber))
    End Sub

End Module

Practical LearningPractical Learning: Reading Numeric Values

  1. To retrieve various numbers from the user, change the file as follows: 
    Module OrderProcessing

    Sub Main() 
        ' Price of items
        Const PriceOneShirt As Double = 0.95D
        Const PriceAPairOfPants As Double = 2.95D
        Const PriceOneDress As Double = 4.55D
        Const TaxRate As Double = 0.0575D  ' 5.75%

        ' Customer personal infoirmation
        Dim CustomerName As String
        Dim HomePhone As String
        ' Unsigned numbers to represent cleaning items
        Dim NumberOfShirts As Integer
        Dim NumberOfPants As Integer
        Dim NumberOfDresses As Integer
        ' Each of these sub totals will be used for cleaning items
        Dim SubTotalShirts As Double
        Dim SubTotalPants As Double
        Dim SubTotalDresses As Double
        ' Values used to process an order
        Dim TotalOrder As Double
        Dim TaxAmount As Double
        Dim SalesTotal As Double
        Dim AmountTended As Double
        Dim Difference As Double

        Console.WriteLine("-/- Georgetown Cleaning Services -/-")
        ' Request customer information from the user
        Console.Write("Enter Customer Name:  ")
        CustomerName = Console.ReadLine()
        Console.Write("Enter Customer Phone: ")
        HomePhone = Console.ReadLine()

        ' Request the quantity of each category of items
        Console.Write("Number of Shirts:  ")
        Dim strShirts As String = Console.ReadLine()
        NumberOfShirts = CInt(strShirts)

        Console.Write("Number of Pants:   ")
        Dim strPants As String = Console.ReadLine()
        NumberOfPants = CInt(strPants)

        Console.Write("Number of Dresses: ")
        Dim strDresses As String = Console.ReadLine()
        NumberOfDresses = CInt(strDresses)

        ' Perform the necessary calculations
        SubTotalShirts = NumberOfShirts * PriceOneShirt
        SubTotalPants = NumberOfPants * PriceAPairOfPants
        SubTotalDresses = NumberOfDresses * PriceOneDress
        ' Calculate the "temporary" total of the order
        TotalOrder = SubTotalShirts + SubTotalPants + SubTotalDresses

        ' Calculate the tax amount using a constant rate
        TaxAmount = TotalOrder * TaxRate
        ' Add the tax amount to the total order
        SalesTotal = TotalOrder + TaxAmount

        ' Communicate the total to the user...
        Console.Write("\nThe Total order is: ")
        Console.WriteLine(SalesTotal)
        ' and request money for the order
        Console.Write("Amount Tended? ")
        AmountTended = CDbl(Console.ReadLine())

        ' Calculate the difference owed to the customer
        ' or that the customer still owes to the store
        Difference = AmountTended - SalesTotal
        Console.WriteLine()

        ' Display the receipt
        Console.WriteLine("====================================")
        Console.WriteLine("-/- Georgetown Cleaning Services -/-")
        Console.WriteLine("====================================")
        Console.WriteLine("Customer:   " + CustomerName)
        Console.WriteLine("Home Phone: " + HomePhone)
        Console.WriteLine("------------------------------------")
        Console.WriteLine("Item Type  Qty Unit/Price Sub-Total")
        Console.WriteLine("------------------------------------")
        Console.Write("Shirts      ")
        Console.Write(NumberOfShirts)
        Console.Write("     ")
        Console.Write(PriceOneShirt)
        Console.Write("     ")
        Console.WriteLine(SubTotalShirts)
        Console.Write("Pants       ")
        Console.Write(NumberOfPants)
        Console.Write("     ")
        Console.Write(PriceAPairOfPants)
        Console.Write("     ")
        Console.WriteLine(SubTotalPants)
        Console.Write("Dresses     ")
        Console.Write(NumberOfDresses)
        Console.Write("     ")
        Console.Write(PriceOneDress)
        Console.Write("     ")
        Console.WriteLine(SubTotalDresses)
        Console.WriteLine("------------------------------------")
        Console.WriteLine("Total Order:     " + CStr(TotalOrder))
        Console.WriteLine("Tax Rate:        " + CStr(TaxRate * 100) + "%")
        Console.WriteLine("Tax Amount:      " + CStr(TaxAmount))
        Console.WriteLine("Net Price:       " + CStr(SalesTotal))
        Console.WriteLine("------------------------------------")
        Console.WriteLine("Amount Tended:   " + CStr(AmountTended))
        Console.WriteLine("Difference:      " + CStr(Difference))
        Console.WriteLine("====================================")
    End Sub

End Module
  2. Execute the application
  3. Enter the requested values. Here is an example of running the program: 
    -/- Georgetown Cleaning Services -/-
Enter Customer Name:  Genevieve Alton
Enter Customer Phone: (202) 974-8244
Number of Shirts:  8
Number of Pants:   2
Number of Dresses: 3

The Total order is: 28.711125
Amount Tended? 30

====================================
-/- Georgetown Cleaning Services -/-
====================================
Customer:   Genevieve Alton
Home Phone: (202) 974-8244
------------------------------------
Item Type  Qty Unit/Price Sub-Total
------------------------------------
Shirts      8     0.95     7.60
Pants       2     2.95     5.90
Dresses     3     4.55     13.65
------------------------------------
Total Order:     27.15
Tax Rate:        5.7500%
Tax Amount:      1.561125
Net Price:       28.711125
------------------------------------
Amount Tended:   30
Difference:      1.288875
====================================
  4. Return to your programming environment

Requesting Dates and Times

As done with the regular numbers, you can request a date value from the user. This is also done by requesting a string from the user. Here is an example:

Module Module1

    Sub Main()
        Dim strDateHired As String

        strDateHired = Console.ReadLine()
    End Sub

End Module

After the user has entered the string you can then convert it to a Date value using CDate() as we mentioned in Lesson 2.

By default, if you request only a date from the user and the user enters a valid date, the compiler would add the midnight value to the date. If you request only the time from the user and the user enters a valid time, the compiler would add the current date to the value. Later on, we will learn how to isolate either only the date or only the time.

Practical LearningPractical Learning: Requesting Date and Time Values

  1. To deal with dates and times, change the program as follows: 
    Module OrderProcessing

    Sub Main() 
        ' Price of items
        Const PriceOneShirt As Double = 0.95D
        Const PriceAPairOfPants As Double = 2.95D
        Const PriceOneDress As Double = 4.55D
        Const TaxRate As Double = 0.0575D  ' 5.75%

        ' Customer personal infoirmation
        Dim CustomerName As String
        Dim HomePhone As String
        Dim OrderDate As Date

        ' Unsigned numbers to represent cleaning items
        Dim NumberOfShirts As Integer
        Dim NumberOfPants As Integer
        Dim NumberOfDresses As Integer
        ' Each of these sub totals will be used for cleaning items
        Dim SubTotalShirts As Double
        Dim SubTotalPants As Double
        Dim SubTotalDresses As Double
        ' Values used to process an order
        Dim TotalOrder As Double
        Dim TaxAmount As Double
        Dim SalesTotal As Double
        Dim AmountTended As Double
        Dim Difference As Double

        Console.WriteLine("-/- Georgetown Cleaning Services -/-")
        ' Request customer information from the user
        Console.Write("Enter Customer Name:  ")
        CustomerName = Console.ReadLine()
        Console.Write("Enter Customer Phone: ")
        HomePhone = Console.ReadLine()
        Console.WriteLine( & _
	    "Enter the order date and time (mm/dd/yyyy hh:mm AM/PM)")
        OrderDate = CDate(Console.ReadLine())

        ' Request the quantity of each category of items
        Console.Write("Number of Shirts:  ")
        Dim strShirts As String = Console.ReadLine()
        NumberOfShirts = CInt(strShirts)

        Console.Write("Number of Pants:   ")
        Dim strPants As String = Console.ReadLine()
        NumberOfPants = CInt(strPants)

        Console.Write("Number of Dresses: ")
        Dim strDresses As String = Console.ReadLine()
        NumberOfDresses = CInt(strDresses)

        ' Perform the necessary calculations
        SubTotalShirts = NumberOfShirts * PriceOneShirt
        SubTotalPants = NumberOfPants * PriceAPairOfPants
        SubTotalDresses = NumberOfDresses * PriceOneDress
        ' Calculate the "temporary" total of the order
        TotalOrder = SubTotalShirts + SubTotalPants + SubTotalDresses

        ' Calculate the tax amount using a constant rate
        TaxAmount = TotalOrder * TaxRate
        ' Add the tax amount to the total order
        SalesTotal = TotalOrder + TaxAmount

        ' Communicate the total to the user...
        Console.Write("\nThe Total order is: ")
        Console.WriteLine(SalesTotal)
        ' and request money for the order
        Console.Write("Amount Tended? ")
        AmountTended = CDbl(Console.ReadLine())

        ' Calculate the difference owed to the customer
        ' or that the customer still owes to the store
        Difference = AmountTended - SalesTotal
        Console.WriteLine()

        ' Display the receipt
        Console.WriteLine("====================================")
        Console.WriteLine("-/- Georgetown Cleaning Services -/-")
        Console.WriteLine("====================================")
        Console.WriteLine("Customer:   " + CustomerName)
        Console.WriteLine("Home Phone: " + HomePhone)
        Console.WriteLine("Date & Time: " + CStr(OrderDate))
        Console.WriteLine("------------------------------------")
        Console.WriteLine("Item Type  Qty Unit/Price Sub-Total")
        Console.WriteLine("------------------------------------")
        Console.Write("Shirts      ")
        Console.Write(NumberOfShirts)
        Console.Write("     ")
        Console.Write(PriceOneShirt)
        Console.Write("     ")
        Console.WriteLine(SubTotalShirts)
        Console.Write("Pants       ")
        Console.Write(NumberOfPants)
        Console.Write("     ")
        Console.Write(PriceAPairOfPants)
        Console.Write("     ")
        Console.WriteLine(SubTotalPants)
        Console.Write("Dresses     ")
        Console.Write(NumberOfDresses)
        Console.Write("     ")
        Console.Write(PriceOneDress)
        Console.Write("     ")
        Console.WriteLine(SubTotalDresses)
        Console.WriteLine("------------------------------------")
        Console.WriteLine("Total Order:     " + CStr(TotalOrder))
        Console.WriteLine("Tax Rate:        " + CStr(TaxRate * 100) + "%")
        Console.WriteLine("Tax Amount:      " + CStr(TaxAmount))
        Console.WriteLine("Net Price:       " + CStr(SalesTotal))
        Console.WriteLine("------------------------------------")
        Console.WriteLine("Amount Tended:   " + CStr(AmountTended))
        Console.WriteLine("Difference:      " + CStr(Difference))
        Console.WriteLine("====================================")
    End Sub

End Module
  2. Execute the project
  3. Enter the requested values. Here is an example of running the program: 
    -/- Georgetown Cleaning Services -/-
Enter Customer Name:  Alexander Pappas
Enter Customer Phone: (301) 397-9764
Enter the order date and time (mm/dd/yyyy hh:mm AM/PM)
06/22/98 08:26 AM
Number of Shirts:  2
Number of Pants:   6
Number of Dresses: 0

The Total order is: 20.727000
Amount Tended? 50

====================================
-/- Georgetown Cleaning Services -/-
====================================
Customer:    Alexander Pappas
Home Phone:  (301) 397-9764
Date & Time: 6/22/1998 8:26:00 AM
------------------------------------
Item Type  Qty Unit/Price Sub-Total
------------------------------------
Shirts      2     0.95     1.90
Pants       6     2.95     17.70
Dresses     0     4.55     0
------------------------------------
Total Order:     19.60
Tax Rate:        5.7500%
Tax Amount:      1.127000
Net Price:       20.727000
------------------------------------
Amount Tended:   50
Difference:      29.273000
====================================
  4. Return to your programming environment

Formatting Data Display

Introduction

Instead of using two Write() or a combination of Write() and WriteLine() to display data, you can convert a value to a string and display it directly. To do this, you can provide two strings to the Write() or WriteLine() and separate them with a comma:

  1. The first part of the string provided to Write() or WriteLine() is the complete string that would display to the user. This first string itself can be made of different sections:
    1. One section is a string in any way you want it to display
    2. Another section is a number included between an opening curly bracket "{" and a closing curly bracket "}". This combination of "{" and "}" is referred to as a placeholder

      You can put the placeholder anywhere inside of the string. The first placeholder must have number 0. The second must have number 1, etc. With this technique, you can create the string anyway you like and use the placeholders anywhere inside of the string
  2. The second part of the string provided to Write() or WriteLine() is the value that you want to display. It can be one value if you used only one placeholder with 0 in the first string. If you used different placeholders, you can then provide a different value for each one of them in this second part, separating the values with a comma

Here are examples:

Module Module1

    Sub Main()
        Dim FullName As String = "Anselme Bogos"
        Dim Age As Integer = 15
        Dim HSalary As Double = 22.74

        Console.WriteLine("Full Name: {0}", FullName)
        Console.WriteLine("Age: {0}", Age)
        Console.WriteLine("Distance: {0}", HSalary)
    End Sub

End Module

This would produce:

Full Name: Anselme Bogos
Age: 15
Distance: 22.74

As mentioned already, the numeric value typed in the curly brackets of the first part is an ordered number. If you want to display more than one value, provide each incremental value in its curly brackets. The syntax used is:

Write("To Display {0} {1} {2} {n}", First, Second, Third, nth)

You can use the sections between a closing curly bracket and an opening curly bracket to create a meaningful sentence.

Practical LearningPractical Learning: Displaying Data With Placeholders

  1. To use curly brackets to display data, change the file as follows: 
    Module OrderProcessing

    Sub Main() 
        ' Price of items
        Const PriceOneShirt As Double = 0.95D
        Const PriceAPairOfPants As Double = 2.95D
        Const PriceOneDress As Double = 4.55D
        Const TaxRate As Double = 0.0575D  ' 5.75%

        ' Customer personal infoirmation
        Dim CustomerName As String
        Dim HomePhone As String
        Dim OrderDate As Date

        ' Unsigned numbers to represent cleaning items
        Dim NumberOfShirts As Integer
        Dim NumberOfPants As Integer
        Dim NumberOfDresses As Integer
        ' Each of these sub totals will be used for cleaning items
        Dim SubTotalShirts As Double
        Dim SubTotalPants As Double
        Dim SubTotalDresses As Double
        ' Values used to process an order
        Dim TotalOrder As Double
        Dim TaxAmount As Double
        Dim SalesTotal As Double
        Dim AmountTended As Double
        Dim Difference As Double

        Console.WriteLine("-/- Georgetown Cleaning Services -/-")
        ' Request customer information from the user
        Console.Write("Enter Customer Name:  ")
        CustomerName = Console.ReadLine()
        Console.Write("Enter Customer Phone: ")
        HomePhone = Console.ReadLine()
        Console.WriteLine("Enter the order date and time " & _
			  "(mm/dd/yyyy hh:mm AM/PM)")
        OrderDate = CDate(Console.ReadLine())

        ' Request the quantity of each category of items
        Console.Write("Number of Shirts:  ")
        Dim strShirts As String = Console.ReadLine()
        NumberOfShirts = CInt(strShirts)

        Console.Write("Number of Pants:   ")
        Dim strPants As String = Console.ReadLine()
        NumberOfPants = CInt(strPants)

        Console.Write("Number of Dresses: ")
        Dim strDresses As String = Console.ReadLine()
        NumberOfDresses = CInt(strDresses)

        ' Perform the necessary calculations
        SubTotalShirts = NumberOfShirts * PriceOneShirt
        SubTotalPants = NumberOfPants * PriceAPairOfPants
        SubTotalDresses = NumberOfDresses * PriceOneDress
        ' Calculate the "temporary" total of the order
        TotalOrder = SubTotalShirts + SubTotalPants + SubTotalDresses

        ' Calculate the tax amount using a constant rate
        TaxAmount = TotalOrder * TaxRate
        ' Add the tax amount to the total order
        SalesTotal = TotalOrder + TaxAmount

        ' Communicate the total to the user...
        Console.Write("\nThe Total order is: ")
        Console.WriteLine(SalesTotal)
        ' and request money for the order
        Console.Write("Amount Tended? ")
        AmountTended = CDbl(Console.ReadLine())

        ' Calculate the difference owed to the customer
        ' or that the customer still owes to the store
        Difference = AmountTended - SalesTotal
        Console.WriteLine()

        ' Display the receipt
        Console.WriteLine("====================================")
        Console.WriteLine("-/- Georgetown Cleaning Services -/-")
        Console.WriteLine("====================================")
        Console.WriteLine("Customer:    {0}", CustomerName)
        Console.WriteLine("Home Phone:  {0}", HomePhone)
        Console.WriteLine("Date & Time: {0}", OrderDate)
        Console.WriteLine("------------------------------------")
        Console.WriteLine("Item Type  Qty Unit/Price Sub-Total")
        Console.WriteLine("------------------------------------")
        Console.WriteLine("Shirts      {0}     {1}     {2}", _
          NumberOfShirts, PriceOneShirt, SubTotalShirts)
        Console.WriteLine("Pants       {0}     {1}     {2}", _
          NumberOfPants, PriceAPairOfPants, SubTotalPants)
        Console.WriteLine("Dresses     {0}     {1}     {2}", _
                   NumberOfDresses, PriceOneDress, SubTotalDresses)
        Console.WriteLine("------------------------------------")
        Console.WriteLine("Total Order:     {0}", TotalOrder)
        Console.WriteLine("Tax Rate:        {0}%", TaxRate * 100)
        Console.WriteLine("Tax Amount:      {0}", TaxAmount)
        Console.WriteLine("Net Price:       {0}", SalesTotal)
        Console.WriteLine("------------------------------------")
        Console.WriteLine("Amount Tended:   {0}", AmountTended)
        Console.WriteLine("Difference:      {0}", Difference)
        Console.WriteLine("====================================")
    End Sub

End Module
  2. Execute the program
  3. Enter the requested values as done previously
  4. Return to your programming environment

Conversion To String

We mentioned earlier that everything the user types using the keyboard is primarily a string and it's your job to convert it to the appropriate type. In reverse, if you have a value that is not a string, you can easily convert it to a string. To support this, we saw in the previous lesson that each data type is equipped with ToString.

To convert value of a primitive data type to a string, type the name of the variable, followed by a period, followed, followed by ToString(). Here is an example:

Module Module1

    Sub Main()
        Dim FullName As String = "Anselme Bogos"
        Dim Age As Integer = 15
        Dim HSalary As Double = 22.74

        Console.WriteLine("Full Name: {0}", FullName)
        Console.WriteLine("Age: {0}", Age.ToString())
        Console.WriteLine("Distance: {0}", HSalary.ToString())
    End Sub

End Module

In some cases, you will type something in the parentheses of ToString().

Number Formatting

To properly display data in a friendly and most familiar way, you can format it. Formatting tells the compiler what kind of data you are using and how you want the compiler to display it to the user. As it happens, you can display a natural number in a common value or, depending on the circumstance, you may prefer to show it as a hexadecimal value. When it comes to double-precision numbers, you may want to display a distance with three values on the right side of the decimal separator and in some cases, you may want to display a salary with only 2 decimal places.

The System namespace provides a specific letter that you can use in the Write() or WriteLine()'s placeholder for each category of data to display. To format a value, in the placeholder of the variable or value, after the number, type a colon and one of the appropriate letter from the following table. If you are using ToString(), then, in the parentheses of ToString(), you can include a specific letter or combination inside of double-quotes. The letters and their meanings are:

  Character Used For
  c C Currency values
  d D Decimal numbers
  e E Scientific numeric display such as 1.45e5
  f F Fixed decimal numbers
  g G General and most common type of numbers
  n N Natural numbers
  r R Roundtrip formatting
  x X Hexadecimal formatting
  p P Percentages

Here are examples:

Module Module1

    Sub Main()
        Dim Distance As Double = 248.38782
        Dim Age As Integer = 15
        Dim NewColor As Integer = 3478
        Dim HourlySalary As Double = 22.74
        Dim HoursWorked As Double = 35.5018473
        Dim WeeklySalary As Double = HourlySalary * HoursWorked

        Console.WriteLine("Distance: {0}", Distance.ToString("E"))
        Console.WriteLine("Age: {0}", Age.ToString())
        Console.WriteLine("Color: {0}", NewColor.ToString("X"))
        Console.WriteLine("Weekly Salary: {0} for {1} hours", _
                           WeeklySalary.ToString("c"), HoursWorked.ToString("F"))
    End Sub

End Module

This would produce:

Distance: 2.483878E+002
Age: 15
Color: D96
Weekly Salary: $807.31 for 35.50 hours

As you may have noticed, if you leave the parentheses of ToString() empty, the compiler would use a default formatting to display the value.

As opposed to calling ToString(), you can use the above letters in the curly brackets of the first part of Write() or WriteLine(). In this case, after the number in the curly brackets, type the colon operator followed by the letter.

Practical LearningPractical Learning: Formatting Data Display

  1. To format data display, change the file as follows: > 
    Module OrderProcessing

    Sub Main() 
        ' Price of items
	Const PriceOneShirt As Double     = 0.95D
	Const PriceAPairOfPants As Double = 2.95D
	Const PriceOneDress As Double     = 4.55D
	Const TaxRate As Double           = 0.0575D  ' 5.75%

	' Customer personal infoirmation
	Dim CustomerName As String
	Dim HomePhone As String
	Dim OrderDate As Date 

	' Unsigned numbers to represent cleaning items
	Dim NumberOfShirts As Integer
	Dim NumberOfPants As Integer
	Dim NumberOfDresses As Integer
	' Each of these sub totals will be used for cleaning items
	Dim SubTotalShirts As Double
	Dim SubTotalPants As Double
	Dim SubTotalDresses As Double
	' Values used to process an order
	Dim TotalOrder As Double
	Dim TaxAmount As Double
	Dim SalesTotal As Double
	Dim AmountTended As Double
	Dim Difference As Double

	Console.WriteLine("-/- Georgetown Cleaning Services -/-")
	' Request customer information from the user
	Console.Write("Enter Customer Name:  ")
	CustomerName = Console.ReadLine()
	Console.Write("Enter Customer Phone: ")
	HomePhone = Console.ReadLine()
	Console.WriteLine("Enter the order date and time " & _
			  "(mm/dd/yyyy hh:mm AM/PM)")
	OrderDate = CDate(Console.ReadLine())
			
	' Request the quantity of each category of items
	Console.Write("Number of Shirts:  ")
	Dim strShirts As String = Console.ReadLine()
	NumberOfShirts   = CInt(strShirts)
			
	Console.Write("Number of Pants:   ")
	Dim strPants As String = Console.ReadLine()
	NumberOfPants    = CInt(strPants)
			
	Console.Write("Number of Dresses: ")
	Dim strDresses As String = Console.ReadLine()
	NumberOfDresses   = CInt(strDresses)
			
	' Perform the necessary calculations
	SubTotalShirts  = NumberOfShirts  * PriceOneShirt
	SubTotalPants   = NumberOfPants   * PriceAPairOfPants
	SubTotalDresses = NumberOfDresses * PriceOneDress
	' Calculate the "temporary" total of the order
	TotalOrder      = SubTotalShirts + SubTotalPants + SubTotalDresses

	' Calculate the tax amount using a constant rate
	TaxAmount       = TotalOrder * TaxRate
	' Add the tax amount to the total order
	SalesTotal      = TotalOrder + TaxAmount

	' Communicate the total to the user...
	Console.Write("\nThe Total order is: ")
	Console.WriteLine(SalesTotal)
	' and request money for the order
	Console.Write("Amount Tended? ")
	AmountTended    = CDbl(Console.ReadLine())

	' Calculate the difference owed to the customer
	' or that the customer still owes to the store
	Difference      = AmountTended - SalesTotal
	Console.WriteLine()

	' Display the receipt
	Console.WriteLine("====================================")
	Console.WriteLine("-/- Georgetown Cleaning Services -/-")
	Console.WriteLine("====================================")
	Console.WriteLine("Customer:    {0}", CustomerName)
	Console.WriteLine("Home Phone:  {0}", HomePhone)
	Console.WriteLine("Date & Time: {0}", OrderDate)
	Console.WriteLine("------------------------------------")
	Console.WriteLine("Item Type  Qty Unit/Price Sub-Total")
	Console.WriteLine("------------------------------------")
	Console.WriteLine("Shirts      {0}     {1:C}     {2}", _
			NumberOfShirts, PriceOneShirt, SubTotalShirts.ToString("C"))
	Console.WriteLine("Pants       {0}     {1}     {2:C}", _
			NumberOfPants, PriceAPairOfPants.ToString("C"), SubTotalPants)
	Console.WriteLine("Dresses     {0}     {1:C}     {2:C}", _
		          NumberOfDresses, PriceOneDress, SubTotalDresses)
	Console.WriteLine("------------------------------------")
	Console.WriteLine("Total Order:     {0:C}", TotalOrder)
	Console.WriteLine("Tax Rate:        {0:P}", TaxRate)
	Console.WriteLine("Tax Amount:      {0}", TaxAmount.ToString("C"))
	Console.WriteLine("Net Price:       {0:F}", SalesTotal)
	Console.WriteLine("------------------------------------")
	Console.WriteLine("Amount Tended:   {0:C}", AmountTended)
	Console.WriteLine("Difference:      {0:C}", Difference)
	Console.WriteLine("====================================")

        Return 0
    End Function

End Module
  2. Save it and switch to the Command Prompt. Then compile the file and execute the application. Here is an example: 
    -/- Georgetown Cleaning Services -/-
Enter Customer Name:  Gretchen McCormack
Enter Customer Phone: (410) 739-2884
Enter the order date and time (mm/dd/yyyy hh:mm AM/PM)
04/09/2001 10:25 AM
Number of Shirts:  5
Number of Pants:   12
Number of Dresses: 8

The Total order is: 80.951625
Amount Tended? 100

====================================
-/- Georgetown Cleaning Services -/-
====================================
Customer:    Gretchen McCormack
Home Phone:  (410) 739-2884
Date & Time: 4/9/2001 10:25:00 AM
------------------------------------
Item Type  Qty Unit/Price Sub-Total
------------------------------------
Shirts      5     $0.95     $4.75
Pants       12     $2.95     $35.40
Dresses     8     $4.55     $36.40
------------------------------------
Total Order:     $76.55
Tax Rate:        5.75 %
Tax Amount:      $4.40
Net Price:       80.95
------------------------------------
Amount Tended:   $100.00
Difference:      $19.05
====================================
  3. Return to your programming environment

Line Formatting

In the above programs, to display a line of text, we easily used Write() or WriteLine(). To position text of different lengths one above the other, we had to "corrupt" a string by including extra-empty spaces. Such a technique is uncertain and less professional. Fortunately, you can highly format how a string or a line of text should display. The .NET Framework provides mechanisms to control the amount of space used to display a string of text and how to align that string on its line.

To specify the amount of space used to display a string, you can use its placeholder in Write() or WriteLine(). To do this, in the placeholder, type the 0 or the incrementing number of the placer and its formatting character if necessary and if any. Then, type a comma followed by the number of characters equivalent to the desired width. Here are examples:

Module Module1

    Sub Main()
        Dim FullName As String = "Anselme Bogos"
        Dim Age As Integer = 15
        Dim HourlySalary As Double = 22.74

        Console.WriteLine("Full Name: {0,20}", FullName)
        Console.WriteLine("Age:{0,14}", Age.ToString())
        Console.WriteLine("Distance: {0:C,8}", HourlySalary.ToString())
    End Sub

End Module

This would produce:

Full Name:        Anselme Bogos
Age:            15
Distance: 22.74

The sign you provide for the width is very important. If it is positive, the line of text is aligned to the right. This should be your preferred alignment for numeric values. If the number is negative, then the text is aligned to the left.

Data and Time Formatting

As mentioned earlier, when the user enters a date value for a DateTime variable, the compiler adds a time part to the value. Fortunately, if you want to consider only the date or only the time part, you can specify this to the compiler. To support this, the DateTime data type provides a series of letters you can use to format how its value should be displayed to the user. The character is entered in the placeholder of the DateTime variable after the 0 or the incremental numeric value.

Practical LearningPractical Learning: Controlling Date/Time Formatting

  1. To control formatting of date and time, change the file as follows: 
    Module OrderProcessing

    Sub Main() 
        ' Price of items
	Const PriceOneShirt As Double     = 0.95D
	Const PriceAPairOfPants As Double = 2.95D
	Const PriceOneDress As Double     = 4.55D
	Const TaxRate As Double           = 0.0575D  ' 5.75%

	' Customer personal infoirmation
	Dim CustomerName As String
	Dim HomePhone As String
	Dim OrderDate As Date
	Dim OrderTime As Date

	' Unsigned numbers to represent cleaning items
	Dim NumberOfShirts As Integer
	Dim NumberOfPants As Integer
	Dim NumberOfDresses As Integer
	' Each of these sub totals will be used for cleaning items
	Dim SubTotalShirts As Double
	Dim SubTotalPants As Double
	Dim SubTotalDresses As Double
	' Values used to process an order
	Dim TotalOrder As Double
	Dim TaxAmount As Double
	Dim SalesTotal As Double
	Dim AmountTended As Double
	Dim Difference As Double

	Console.WriteLine("-/- Georgetown Cleaning Services -/-")
	' Request customer information from the user
	Console.Write("Enter Customer Name:  ")
	CustomerName = Console.ReadLine()
	Console.Write("Enter Customer Phone: ")
	HomePhone = Console.ReadLine()
	Console.Write("Enter the order date(mm/dd/yyyy):  ")
	OrderDate = CDate(Console.ReadLine())
	Console.Write("Enter the order time(hh:mm AM/PM): ")
	OrderTime = CDate(Console.ReadLine())
			
	' Request the quantity of each category of items
	Console.Write("Number of Shirts:  ")
	Dim strShirts As String = Console.ReadLine()
	NumberOfShirts   = CInt(strShirts)
			
	Console.Write("Number of Pants:   ")
	Dim strPants As String = Console.ReadLine()
	NumberOfPants    = CInt(strPants)
			
	Console.Write("Number of Dresses: ")
	Dim strDresses As String = Console.ReadLine()
	NumberOfDresses   = CInt(strDresses)
			
	' Perform the necessary calculations
	SubTotalShirts  = NumberOfShirts  * PriceOneShirt
	SubTotalPants   = NumberOfPants   * PriceAPairOfPants
	SubTotalDresses = NumberOfDresses * PriceOneDress
	' Calculate the "temporary" total of the order
	TotalOrder      = SubTotalShirts + SubTotalPants + SubTotalDresses

	' Calculate the tax amount using a constant rate
	TaxAmount       = TotalOrder * TaxRate
	' Add the tax amount to the total order
	SalesTotal      = TotalOrder + TaxAmount

	' Communicate the total to the user...
	Console.Write("\nThe Total order is: ")
	Console.WriteLine(SalesTotal)
	' and request money for the order
	Console.Write("Amount Tended? ")
	AmountTended    = CDbl(Console.ReadLine())

	' Calculate the difference owed to the customer
	' or that the customer still owes to the store
	Difference      = AmountTended - SalesTotal
	Console.WriteLine()

	' Display the receipt
	Console.WriteLine("====================================")
	Console.WriteLine("-/- Georgetown Cleaning Services -/-")
	Console.WriteLine("====================================")
	Console.WriteLine("Customer:    {0}", CustomerName)
	Console.WriteLine("Home Phone:  {0}", HomePhone)
	Console.WriteLine("Order Date:  {0:D}", OrderDate)
	Console.WriteLine("Order Time:  {0:t}", OrderTime)
	Console.WriteLine("------------------------------------")
	Console.WriteLine("Item Type  Qty Unit/Price Sub-Total")
	Console.WriteLine("------------------------------------")
	Console.WriteLine("Shirts      {0}     {1:C}     {2}", _
		NumberOfShirts, PriceOneShirt, SubTotalShirts.ToString("C"))
	Console.WriteLine("Pants       {0}     {1}     {2}", _
			NumberOfPants, PriceAPairOfPants, SubTotalPants)
	Console.WriteLine("Dresses     {0}     {1:C}     {2:C}", _
		          NumberOfDresses, PriceOneDress, SubTotalDresses)
	Console.WriteLine("------------------------------------")
	Console.WriteLine("Total Order:     {0:C}", TotalOrder)
	Console.WriteLine("Tax Rate:        {0:P}", TaxRate)
	Console.WriteLine("Tax Amount:      {0}", TaxAmount.ToString("C"))
	Console.WriteLine("Net Price:       {0:F}", SalesTotal)
	Console.WriteLine("------------------------------------")
	Console.WriteLine("Amount Tended:   {0:C}", AmountTended)
	Console.WriteLine("Difference:      {0:C}", Difference)
	Console.WriteLine("====================================")

        Return 0
    End Function

End Module
  2. Save, compile, and run the program. Here is an example: 
    -/- Georgetown Cleaning Services -/-
Enter Customer Name:  Antoinette Calhoun
Enter Customer Phone: (703) 797-1135
Enter the order date(mm/dd/yyyy):  04/12/2002
Enter the order time(hh:mm AM/PM): 2:12 PM
Number of Shirts:  5
Number of Pants:   2
Number of Dresses: 1

The Total order is: $16.07
Amount Tended? 20

====================================
-/- Georgetown Cleaning Services -/-
====================================
Customer:    Antoinette Calhoun
Home Phone:  (703) 797-1135
Order Date:  Friday, April 12, 2002
Order Time:  2:12 PM
------------------------------------
Item Type  Qty Unit/Price Sub-Total
------------------------------------
Shirts     5   $0.95       $4.75
Pants      2   $2.95        $5.90
Dresses    1   $4.55        $4.55
------------------------------------
Total Order:   $15.20
Tax Rate:      5.75 %
Tax Amount:    $0.87
Net Price:     $16.07
------------------------------------
Amount Tended: $20.00
Difference:    $3.93
====================================
  3. Return to your programming environment
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