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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:
- 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:
- One section is a string in any way you want it to
display
- 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
- 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
Learning: Displaying Data With Placeholders
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- To use curly brackets to display data, change the file as follows:
Module OrderProcessing
Public Function Main() As Integer
' 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("====================================")
Return 0
End Function
End Module
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- Execute the program
- Enter the requested values as done previously
- Return to your programming environment
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().
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
Learning: Formatting Data Display |
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- To format data display, change the file as follows:
Module OrderProcessing
Public Function Main() As Integer
' 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
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- 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
====================================
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- Return to your programming environment
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.
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
Learning: Controlling Date/Time Formatting |
|
- To control formatting of date and time, change the file as follows:
Module OrderProcessing
Public Function Main() As Integer
' 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
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- 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
====================================
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- Return to your programming environment
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