|
This simply means that, when the user types something
and presses Enter, what the user had typed would be given (the word is 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 some
versions of C# (even including Microsoft's C# and Borland C#Builder) would display the DOS
window briefly and disappear. 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 the ReadLine() method. Like the WriteLine() member
function, after
performing its assignment, the ReadLine() method sends the caret to the
next line. Otherwise, it plays the same role as the Read() function.
|
|
 Practical
Learning: Introducing Data Reading
|
|
- Start Microsoft Visual C# and create a Console
Application named GeorgetownCleaningServices3
- Change the file type as follows:
using System;
namespace GeorgetownCleaningServices3
{
class OrderProcessing
{
static void Main()
{
Console.WriteLine();
}
}
}
|
- Save the file
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:
string FirstName;
Console.Write("Enter First Name: ");
FirstName = Console.ReadLine();
|
Practical
Learning: Reading String Values |
|
- To request strings from the user, change the file as follows:
using System;
namespace GeorgetownCleaningServices3
{
class OrderProcessing
{
static void Main()
{
string CustomerName, HomePhone;
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.Write("Customer: ");
Console.WriteLine(CustomerName);
Console.Write("Home Phone: ");
Console.WriteLine(HomePhone);
Console.WriteLine("====================================\n");
}
}
}
|
- Execute the program. 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
====================================
|
- Close the DOS window
In C#, everything the user types is a string and the
compiler would hardly analyze it without your explicit asking it to do so.
Therefore, if you want to get a number from the user, first request a
string. Here is an example:
using System;
namespace GeorgetownCleaningServices3
{
class OrderProcessing
{
static void Main()
{
int Number;
string strNumber;
strNumber = Console.ReadLine();
}
}
}
After getting the string, you must convert it to a number. To perform this
conversion, each data type of the .NET Framework provides a mechanism
called
Parse. To use
Parse(), type the data type, followed by a period, followed by Parse,
and followed by parentheses. In the parentheses of Parse, type the string
that you requested from the user. Here is an example:
using System;
namespace GeorgetownCleaningServices3
{
class OrderProcessing
{
static void Main()
{
int Number;
string strNumber;
strNumber = Console.ReadLine();
Number = int.Parse(strNumber);
}
}
}
An advanced but faster way to do this is to type Console.ReadLine()
in the parentheses of Parse. This has the same effect. Here is an example:
using System;
namespace GeorgetownCleaningServices3
{
class OrderProcessing
{
static void Main()
{
int Number;
Number = int.Parse(Console.ReadLine());
}
}
}
|
Practical
Learning: Reading Numeric Values |
|
- To retrieve various numbers from the user, change the file as
follows:
using System;
namespace GeorgetownCleaningServices3
{
class OrderProcessing
{
static void Main()
{
// Price of items
const decimal PriceOneShirt = 0.95M;
const decimal PriceAPairOfPants = 2.95M;
const decimal PriceOneDress = 4.55M;
const decimal TaxRate = 0.0575M; // 5.75%
// Customer personal infoirmation
string CustomerName, HomePhone;
// Unsigned numbers to represent cleaning items
uint NumberOfShirts, NumberOfPants, NumberOfDresses;
// Each of these sub totals will be used for cleaning items
decimal SubTotalShirts, SubTotalPants, SubTotalDresses;
// Values used to process an order
decimal TotalOrder, TaxAmount, SalesTotal;
decimal AmountTended, Difference;
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: ");
string strShirts = Console.ReadLine();
NumberOfShirts = uint.Parse(strShirts);
Console.Write("Number of Pants: ");
string strPants = Console.ReadLine();
NumberOfPants = uint.Parse(strPants);
Console.Write("Number of Dresses: ");
string strDresses = Console.ReadLine();
NumberOfDresses = uint.Parse(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 = decimal.Parse(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.Write("Customer: ");
Console.WriteLine(CustomerName);
Console.Write("Home Phone: ");
Console.WriteLine(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.Write("Total Order: ");
Console.WriteLine(TotalOrder);
Console.Write("Tax Rate: ");
Console.Write(TaxRate * 100);
Console.WriteLine('%');
Console.Write("Tax Amount: ");
Console.WriteLine(TaxAmount);
Console.Write("Net Price: ");
Console.WriteLine(SalesTotal);
Console.WriteLine("------------------------------------");
Console.Write("Amount Tended: ");
Console.WriteLine(AmountTended);
Console.Write("Difference: ");
Console.WriteLine(Difference);
Console.WriteLine("====================================");
}
}
}
|
- Eo execute the program and test it. Here is an example:
-/- 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
====================================
|
- Close the DOS window
|
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:
using System;
namespace ValueRequests
{
class Exercise
{
static void Main()
{
string strDateHired;
strDateHired = Console.ReadLine();
}
}
}
After the user has entered the string you can then convert
it to a DateTime value. Just like any value you request from the user, a
date or time value that the user types must be valid, otherwise, the program
would produce an error. Because dates and times follow some rules for their
formats, you should strive to let the user know how you expect the value to be
entered.
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.
|
|
