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Create VB Console Project |
We will start at the root of ALL OUR PROJECTS c:\ZT\> |
CLI: dotnet new console -lang VB -o vbtest1 |
CLI: cd vbtest1 |
CLI: dotnet build |
CLI: dotnet run |
See Appendix 1 for Screenshot of VB Console Project Based On DotNet Framework |
Online code beautifier tool: |
1) Print Hello World Program (VB) |
Pseudo Code: 1. BEGIN 2. PRINT "Hello World" 3. END |
Imports System Module Program Sub Main(args As String()) Console.WriteLine("Hello World!") End Sub End Module |
2) Sum Numbers Program (VB) |
Pseudo Code: 1. BEGIN 2. PRINT 1 + 2 3. END |
CLUE: Console.WriteLine(1+2); |
Imports System Module Program Sub Main(args As String()) Console.WriteLine(1 + 2) Console.ReadKey() End Sub End Module |
3) Sum Variables Program (VB) |
Pseudo Code: 1. BEGIN 2. INPUT var1, var2 3. PRINT var1+var2 4. END |
CLUE: |
Imports System Module Program Sub Main(args As String())
Dim var1 As Integer = Console.ReadLine()
Dim var2 As Integer = Console.ReadLine()
Console.WriteLine(var1 + var2)
Console.ReadKey()
End Sub End Module |
4) Multiply Variables Program (VB) |
Pseudo Code: 1. BEGIN 2. INPUT var1, var2 3. PRINT var1 * var2 4. END |
Imports System Module Program Sub Main(args As String())
Dim var1 As Integer = Console.ReadLine()
Dim var2 As Integer = Console.ReadLine()
Console.WriteLine(var1 * var2)
Console.ReadKey()
End Sub End Module |
5) Divide Variables Program (VB) |
Pseudo Code: 1. BEGIN 2. INPUT var1, var2 3. IF var2=0 4. THEN PRINT "Error. Division by zero." 5. ELSE PRINT var1/var2 6. END |
CLUE: Try input for 2 rounds. For round1 => var1=4, var2=2 For round2=> var1=2, var2=0 |
Imports System Module Program Sub Main(args As String())
Dim var1 As Double = Console.ReadLine()
Dim var2 As Double = Console.ReadLine()
If var2 = 0 Then
Console.WriteLine("Error. Division by zero") Else
Console.WriteLine(var1 / var2)
End If
Console.ReadKey()
End Sub End Module |
6) Count Numbers Program (VB) |
Pseudo Code: 1. BEGIN 2. PRINT "Start counting." 3. FOR i LOOP := 1 to 3 STEP 1 4. PRINT i 5. END LOOP 6. PRINT "Done." 7. END |
CLUE: Note:loop index number starts with 0. |
Imports System Module Program Sub Main(args As String())
Console.WriteLine("Start Counting.")
For i As Integer = 0 To 2 Step 1
Console.WriteLine(i) Next
Console.WriteLine("Start Done.")
End Sub End Module |
7) Display Array Values Program (VB) |
1. BEGIN 2. INITIALISE ARRAY arr[5] TO CONTAIN VALUES a,b,c,d,e 3. PRINT "Displaying array values." 4. FOR i := 1 to 5 5. PRINT arr[i] 6. END FOR LOOP 7. PRINT "Done." 8. END |
CLUE: Plan your data type for array carefully string[] arr = new string[] {"a", "b", "c", "d", "e"}; string[] arr = {"a", "b", "c", "d", "e"}; |
Imports System Module Program Sub Main(args As String())
Dim arr() As String = {"a", "b", "c", "d", "e"}
Console.WriteLine("Displaying array values.")
For i As Integer = 0 To 4 Step 1
Console.WriteLine(arr(i))
Next
Console.WriteLine("Start Done.")
End Sub End Module |
Imports System Module Program Sub Main(args As String())
Dim arr() As Char = {"a", "b", "c", "d", "e"}
Console.WriteLine("Displaying array values.")
For i As Integer = 0 To 4 Step 1
Console.WriteLine(arr(i))
Next
Console.WriteLine("Start Done.")
End Sub End Module |
8) Edit Array Values Program (VB) |
Pseudo Code: 1. BEGIN 2. INITIALISE ARRAY arr[i] WITH VALUES 1,2,3,4,5 3. FOR i := 1 to 5 4. PRINT arr[i] 5. END FOR LOOP 6. INPUT indexnumber 7. INPUT arrayvalue 8. arr[indexnumber] = arrayvalue 9. FOR i := 1 to 5 10. PRINT arr[i] 11. END FOR LOOP 12. END |
CLUE: Try input 1 and f What is the output? a b c d e Input indexNumber = 1 Input arrayValue = f Let arr[1]=f a f c d e |
Imports System Module Program Sub Main(args As String())
Dim arr() As Char = {"a", "b", "c", "d", "e"}
Console.WriteLine("Displaying array values.") For i As Integer = 0 To 4 Step 1 Console.WriteLine(arr(i)) Next Console.WriteLine("Start Done.")
Console.WriteLine("Enter index number and new value:") Dim indexNumber As Integer = Console.ReadLine() Dim arrayValue As String = Console.ReadLine() arr(indexNumber) = arrayValue
Console.WriteLine("Displaying array values.") For i As Integer = 0 To 4 Step 1 Console.WriteLine(arr(i)) Next Console.WriteLine("Start Done.")
End Sub End Module |
SEBELUM INPUT
arr[0]=a
arr[1]=b
arr[2]=c
arr[3]=d
arr[4]=e
INPUT
indexNumber? Cth 1
arrayValue? Cth f
KEMASKINI NILAI DALAM ARRAY
arr[1]=f
SELEPAS INPUT
arr[0]=a
arr[1]=f
arr[2]=c
arr[3]=d
arr[4]=e
9) Modular Program (VB) |
Pseudo Code: 1. BEGIN displaydata 2. FOR all item in array PRINT item values 3. END displaydata 1. BEGIN updatedata 2. INPUT indexnumber, arrayvalue 3. arr[indexnumber]=arrayvalue 4. CALL displaydata 4. END updatedata 1. BEGIN main 2. CALL displaydata 3. CALL updatedata 4. END main |
CLUE: Main { Dim arr() as Char={"a","b","c","d","e"}; displayData(arr); updateData(arr); displayData(arr); } Sub displayData(ByVal arr() as Char) … End Sub Sub updateData(ByRef arr() as Char){ … End Sub |
Imports System Module Program Sub Main(args As String())
Dim arr() As Char = {"a", "b", "c", "d", "e"} displayData(arr) updateData(arr) displayData(arr)
End Sub Sub displayData(ByVal arr() As Char) Console.WriteLine("Displaying array values.") For i As Integer = 0 To 4 Step 1 Console.WriteLine(arr(i)) Next Console.WriteLine("Start Done.") End Sub Sub updateData (ByRef arr() As Char) Console.WriteLine("Enter index number and new value:") Dim indexNumber As Integer = Console.ReadLine() Dim arrayValue As Char = Console.ReadLine() arr(indexNumber) = arrayValue End Sub End Module |
cd /
cd ZT
cd cstest1
10) Program Parameter (VB) |
Imports System Module Program Sub Main(args As String())
Console.WriteLine(args(0))
End Sub End Module |
Type console command: |
dotnet run hello |
Output: |
TRY CATCH BLOCK (VB) |
Try ‘Try to do something here Catch e As Exception Console.WriteLine(e.Message) End Try |
11) Working With Text File (VB) |
Get back to root of projects C:\ZT> Type command: dotnet new console -lang vb -o vbtrycatch Type command: cd vbtrycatch |
In the VC project explorer panel, find the vbtrycatch folder. You will see Program.vb Create a text file data.txt in the project root folder (i.e. vbtrycatch folder). Type following text into the file (i.e. data.txt): this is a test |
Edit Program.vb by replacing the existing codes with the following codes. |
Imports System Imports System.IO Module Program Sub Main() Dim fileName As String = "data.txt" Try Using writer As StreamReader = New StreamReader(fileName) Dim line As String line = sr.ReadLine() While ( line <> Nothing) Console.WriteLine(line) line = sr.ReadLine() End While End Using Catch e As Exception Console.WriteLine(e.Message) End Try Console.ReadKey() End Sub End Module |
C:\ZT\vbtrycatch>dotnet run This is a test |
Try changing the content of data.txt (e.g. this is another test). Run again your program. Check that new data is displayed. |
C:\ZT\vbycatch>dotnet run This is a another test |
Sending And Receiving Data Through Internet HyperText Transfer Protocol |
Suppose that we want to send data to a target server at the URL https://httpbin.org/post |
For illustration purposes, we will use the REST demo application at https://resttesttest.com as a form tool for data submission to the target server. The target server URL is specifically allocated for the POST method. Sending a FORM method will result with HTTP 200 success code. |
On the other hand, sending a GET method will result in an HTTP 400 error code. |
In the next part, we are going to write a DotNet Console application to work similar to the RestTestTest web site. |
12) Working With Web Request (VB) |
Imports System Imports System.text Imports System.Web Imports System.Net Imports System.IO Module Program Sub Main() Try Dim postdata As String = "comments=good&custemail=harry@porter.com&custname=harry+porter&custtel=0123456789&delivery=jnt" WebrequestWithPost("https://httpbin.org/post",Encoding.UTF8,postdata,"application/x-www-form-urlencoded") Catch e As Exception Console.WriteLine(e.Message) End Try Console.ReadKey() End Sub Function WebrequestWithPost(ByVal url As String, ByVal dataEncoding As Encoding, ByVal dataToPost As String, ByVal contentType As String) As String Dim postDataAsByteArray As Byte() = dataEncoding.GetBytes(dataToPost) Dim returnValue As String = String.Empty Try Dim webRequest As HttpWebRequest = WebRequest.CreateHttp(url) 'change to: dim webRequest as var = DirectCast(WebRequest.Create(url), HttpWebRequest) if you are your .NET Version is lower than 4.5 If (Not (webRequest) Is Nothing) Then webRequest.AllowAutoRedirect = False webRequest.Method = "POST" webRequest.ContentType = contentType webRequest.ContentLength = postDataAsByteArray.Length Dim requestDataStream As Stream = webRequest.GetRequestStream requestDataStream.Write(postDataAsByteArray, 0, postDataAsByteArray.Length) requestDataStream.Close Dim response As Webresponse = webRequest.GetResponse Dim responseDataStream As Stream = response.GetResponseStream If (Not (responseDataStream) Is Nothing) Then Dim responseDataStreamReader As StreamReader = New StreamReader(responseDataStream) returnValue = responseDataStreamReader.ReadToEnd Console.WriteLine(returnValue) responseDataStreamReader.Close responseDataStream.Close End If response.Close requestDataStream.Close End If Catch ex As WebException If (ex.Status = WebExceptionStatus.ProtocolError) Then Dim response As HttpWebResponse = CType(ex.Response,HttpWebResponse) 'handle this your own way. Console.WriteLine("Webexception! Statuscode: {0}, Description: {1}", CType(response.StatusCode,Integer), response.StatusDescription) End If Catch ex As Exception 'handle this your own way, something serious happened here. Console.WriteLine(ex.Message) End Try Return returnValue End Function End Module |
https://codesnippets.fesslersoft.de/send-data-using-a-webrequest/ |
13) SQL Server Connection (VB) |
CLI: dotnet new console -lang c# -o vbdbcon1 |
CLI: dotnet add package Microsoft.Data.SqlClient --version 5.0.0 |
Imports System Imports Microsoft.Data.SqlClient Module Program Sub Main(args As String()) Try
Dim builder As New Microsoft.Data.SqlClient.SqlConnectionStringBuilder()
builder.DataSource = "smacomdb.mssql.somee.com" builder.UserID = "smarcompu_SQLLogin_1" builder.Password = "" builder.InitialCatalog = "smacomdb" builder.TrustServerCertificate = True
Using connection As New SqlConnection(builder.ConnectionString)
Console.WriteLine(vbCrLf & "Query data example:") Console.WriteLine("=========================================" & vbCrLf)
connection.Open()
Dim sql As String = "SELECT name, collation_name FROM sys.databases"
Using command As New SqlCommand(sql,connection)
Using reader As SqlDataReader = command.ExecuteReader() If reader.HasRows Then Do Whilereader.Read 'Console.WriteLine("{0}", reader.GetString(0)) Console.WriteLine($"{reader.GetString(0)}") Loop End If End Using End Using connection.Close() End Using Catch ex As Exception End Try Console.WriteLine(vbCrLf & "Done. Press enter.") Console.ReadLine() End Sub End Module |
CLI: cd vbdbcon1 CLI: dotnet build CLI: dotnet run |
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