Programming in C#
Lab 5
Objectives:
At the end of this session, you will able to understand:
- Namespace
- Exception Handling
Part I: Getting started (60 minutes)
Exercise 1: Using namespace
Step 1: Open Visual Studio
Step 2: Select the menu File->New->Project to create console based project named ‘Namespace’ and Solution named Session05 as following
Step 3: Rename the class file ‘program.cs‘ to ‘Namespace.cs’
Step 4: Replace code in ‘Namespace.cs’ with given code
using System;
using Customer;
using Order;
namespace Customer
{
class Cust_details
{
public string strName;
public void getName()
{
Console.WriteLine("Enter your name :");
strName = Console.ReadLine();
}
}
}
namespace Order
{
class Grocery_items
{
public void Ord_grocery()
{
Cust_details objCust1 = new Cust_details();
objCust1.getName();
Console.WriteLine("Hello {0}", objCust1.strName);
Console.WriteLine("You have ordered grocery items");
}
}
class Bakery_items
{
public void Ord_bakery()
{
Cust_details objCust2 = new Cust_details();
objCust2.getName();
Console.WriteLine("Hello {0}", objCust2.strName);
Console.WriteLine("You have ordered bakery items");
}
}
}
class OrderTest
{
public static void Main()
{
string choice;
Console.WriteLine("What would you like to order? 1-Grocery Items, 2-Bakery Items");
choice = Console.ReadLine();
if (choice == "1")
{
Grocery_items objGrocery = new Grocery_items();
objGrocery.Ord_grocery();
}
else
{
if (choice == "2")
{
Bakery_items objBakery = new Bakery_items();
objBakery.Ord_bakery();
}
else
{
Console.WriteLine("Enter either 1 or 2");
}
}
Console.ReadLine();
}
}
Step 5: Select menu File -> Save to save the file
Step 6: Select Build -> Build ‘Namespace.cs’ option to build the project
Step 7: Select Debug -> Start without Debuging to execute the program
The output of the program as following
Exercise 2: Exception Handling
Step 1: Add a console based project ‘ExHandling1’ to the solution
Step 2: Right click on project ‘ExHandling1’ -> set as Startup project
Step 3: Rename the class file ‘Program.cs’ to ‘ExHandling1.cs’
Step 4: Replace the code in ‘ExHandling1.cs’ with the given code
using System;
using System.Collections.Generic;
using System.Text;
namespace Bai05
{
class Vidu1
{
static void Main(string[] args)
{
byte[] a = new byte[5];
//nhap mang
try
{
for (int i = 0; i <= 5; i++)
{
Console.WriteLine("a[{0}]=", i + 1);
a[i] = Convert.ToByte(Console.ReadLine());
}
}
catch (FormatException ex)
{
//Console.WriteLine(ex.Message);
Console.WriteLine("Khong duoc nhap ki tu cho mang so");
}
catch (OverflowException ex)
{
//Console.WriteLine(ex.Message);
Console.WriteLine("Khong duoc nhap gia tri nam ngoai mien 0-255");
}
catch (IndexOutOfRangeException ex)
{
//Console.WriteLine(ex.Message);
Console.WriteLine("Loi vuot qua pham vi cua mang");
}
//in mang
for (int i = 0; i < 5; i++)
Console.Write(" {0}", a[i]);
}
}
}
Step 5: Select menu File -> Save to save the file
Step 6: Select Build -> Build ‘ExHandling1’ option to build the project
Step 7: Select Debug -> Start without Debuging to execute the program
The output of program as following
Exercise 3: Write a program to accept a number and print multiplication table of that number. Use exception handling to ensure that user enters only numeric values and the number entered is greater than zero.
Step 1: Add a console based project ‘ExHandling2’ to the solution
Step 2: Right click on project ‘ExHandling2’ -> set as Startup project
Step 3: Rename the class file ‘Program.cs’ to ‘ExHandling1.cs’
Step 4: Replace the code in ‘ExHandling2.cs’ with the given code
using System;
public class InvalidInput : ApplicationException
{
public InvalidInput()
: base("Enter a number greater than Zero"){}
}
class TestExcep
{
public static void Main()
{
int intCnt;
int intNum = 0;
Console.WriteLine("Enter a number :");
try
{
intNum = Convert.ToInt32(Console.ReadLine());
if (intNum <= 0)
{
throw new InvalidInput();
}
}
catch (InvalidInput objInvalidInput)
{
Console.WriteLine(objInvalidInput.Message);
}
catch (System.FormatException objFormatException)
{
Console.WriteLine(objFormatException.Message);
}
finally
{
if (intNum > 0)
{
for (intCnt = 1; intCnt <= 10; intCnt++)
Console.WriteLine(intCnt * intNum);
}
}
Console.ReadLine();
}
}
Step 5: Select menu File -> Save to save the file
Step 6: Select Build -> Build ‘ExHandling2’ option to build the project
Step 7: Select Debug -> Start without Debuging to execute the program
The output of program as following
Exercise 4: Throw statement
Step 1: Add a console based project ‘ExHandling3’ to the solution
Step 2: Right click on project ‘ExHandling3’ -> set as Startup project
Step 3: Rename the class file ‘Program.cs’ to ‘ExHandling1.cs’
Step 4: Replace the code in ‘ExHandling3.cs’ with the given code
using System;
class MainClass
{
public static int AnExceptionFunction(int value)
{
if (value == 0) // Can't divide by zero
throw new DivideByZeroException("Divide By 0 error!");
int x = 20 / value;
return x;
}
public static void Main()
{
int value = 0;
try
{
value = AnExceptionFunction(10); // This works ok
Console.WriteLine("Value = {0}", value);
AnExceptionFunction(0); // This doesn't
Console.WriteLine("Value = {0}", value);
}
catch (Exception e)
{
Console.WriteLine("Caught an exception {0}. Continuing", e);
}
Console.WriteLine("Done");
}
}
Step 5: Select menu File -> Save to save the file
Step 6: Select Build -> Build ‘ExHandling3’ option to build the project
Step 7: Select Debug -> Start without Debuging to execute the program
The output of program as following
Exercise 5: Finally statement
Step 1: Add a console based project ‘FinallyStmt’ to the solution
Step 2: Right click on project ‘FinallyStmt -> set as Startup project
Step 3: Rename the class file ‘Program.cs’ to ‘FinallyStmt.cs’
Step 4: Replace the code in ‘FinallyStmt.cs’ with the given code
using System;
using System.IO;
class FinallyDemo
{
static void Main(string[] args)
{
FileStream outStream = null;
FileStream inStream = null;
try
{
//mo file de ghi du lieu
outStream = File.OpenWrite("DestinationFile.txt");
//mo file de doc du lieu
inStream = File.OpenRead("BogusInputFile.txt");
//cac cau lenh doc du lieu tu file
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
finally
{
if (outStream != null)
{
outStream.Close();
Console.WriteLine("outStream closed.");
}
if (inStream != null)
{
inStream.Close();
Console.WriteLine("inStream closed.");
}
}
}
}
The output of program as following
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