How To Convert String To Type Uri (simple)
Apr 23, 2012What is the quickest way to convert a string value of a URL to type URI? VB.NET please..
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Convert String Value To Type And Pass As Type Parameter.
Nov 19, 2010i am getting all filenames from a directory.parsing out the directory names & the .vb extension then converting those filesnames to classes.Every file in the LPCriteria direcotry is its own class with a "Evaluate" function.[code]
View 1 RepliesConvert From Type 'ListItem' To Type 'String'?
Aug 28, 2009In a VS 2008 ASP.net 3.5 aspx.vb file, Response.Write(DDL.SelectedItem) worked very well.But "Dim filenameDDL As String = DDL.SelectedItem.Text" did not. Then I tried the following codes and found the problem -- Conversion from type 'ListItem' to type 'String' is not valid.
[Code]...
C# - Solve This Error "Cannot Convert Lambda Expression To Type 'string' Because It Is Not A Delegate Type"
Jun 12, 2010. I get this error: "Cannot convert lambda expression to type 'string' because it is not a delegate type" - keyword select become underlined in blue
[Code]...
Above code should displays drop list of employees first name and last name in a combo box
Convert A String To Generic Type T When T Is A Valuetype?
May 1, 2012fast way in VB to go from a string to a generic type T constrained to a valuetype (Of T as Structure), when I know that T will always be some number type?This is too slow for my taste:
Return DirectCast(Convert.ChangeType(myStr, GetType(T)), T)
But it seems to be the only sane method of getting from a String --> T. I've tried using Reflector to see how Convert.ChangeType works, and while I can convert from the String to a given number type via a hacked-up version of that code, I have no idea how to jam that type back into T so it can be returned.
I'll add that part of the speed penalty I'm seeing (in a timing loop) is because the return value is getting assigned to a Nullable(Of T) value. If I strongly-type my class for a specific number type (i.e., UInt16), then I can vastly increase the performance, but then the class would need to be duplicated for each numeric type that I use.
It'd almost be nice if there was converter to/from T while working on it in a generic method/class. Maybe there is and I'm oblivious to its existence?
Conclusion:Testing the three provided implementations below and my original DirectCast/ChangeType form, @peenut's approach of using a prepared delegate to fetch the Parse method from a basic type works. No error checking is done, however, so implementors need to remember to only use this with valuetypes that have a Parse method available. Or extend the below to do error checking.
All runs were done on a 32bit system running Windows Server 2003 R2 with 4GB of RAM. Each "run" is 1,000,000 executions (ops) of the method to be tested, timed with StopWatch and reported back in milliseconds.
Original DirectCast(Convert.ChangeType(myStr, GetType(T)), T):
1000000 ops: 597ms
Average of 1000000 ops over 10 runs: 472ms
Average of 1000000 ops over 10 runs: 458ms
[code]....
Comparatively, peenut's approach is almost 200ms faster when executed 1,000,000 times in a tight loop, so his approach wins out.
Convert A Type To String That Can Be Compiled In Program?
Mar 6, 2010I need a function that will convert a type to a string, for example[code]...
View 2 RepliesHow To Convert Boolean Type Into On / Off Using String.Format
Jan 3, 2011Is there are any way to convert boolean type into "ON"/"OFF" using string formatter
Like:
Dim inpValue as Boolean
Dim outValue = String.Format("0:ON;OFF", inpValue)
' should show OFF as output
I cannot use code or IFormatProvider
.net - Faster Way To Convert From A String To Generic Type T When T Is A Valuetype?
Jan 6, 2011Does anyone know of a fast way in VB to go from a string to a generic type T constrained to a valuetype (Of T as Structure), when I know that T will always be some number type?This is too slow for my taste:
Return DirectCast(Convert.ChangeType(myStr, GetType(T)), T)
But it seems to be the only sane method of getting from a String --> T. I've tried using Reflector to see how Convert.ChangeType works, and while I can convert from the String to a given number type via a hacked-up version of that code, I have no idea how to jam that type back into T so it can be returned.
I'll add that part of the speed penalty I'm seeing (in a timing loop) is because the return value is getting assigned to a Nullable(Of T) value. If I strongly-type my class for a specific number type (i.e., UInt16), then I can vastly increase the performance, but then the class would need to be duplicated for each numeric type that I use.
It'd almost be nice if there was converter to/from T while working on it in a generic method/class. Maybe there is and I'm oblivious to its existence?
Conclusion:Testing the three provided implementations below and my original DirectCast/ChangeType form, @peenut's approach of using a prepared delegate to fetch the Parse method from a basic type works. No error checking is done, however, so implementors need to remember to only use this with valuetypes that have a Parse method available. Or extend the below to do error checking.
All runs were done on a 32bit system running Windows Server 2003 R2 with 4GB of RAM. Each "run" is 1,000,000 executions (ops) of the method to be tested, timed with StopWatch and reported back in milliseconds.
Original DirectCast(Convert.ChangeType(myStr, GetType(T)), T):
1000000 ops: 597ms
Average of 1000000 ops over 10 runs: 472ms
Average of 1000000 ops over 10 runs: 458ms
[code]....
Using System.Reflection and calling InvokeMethod to get at the Parse method:
1000000 ops: 12213ms
Average of 1000000 ops over 10 runs: 11468ms
Average of 1000000 ops over 10 runs: 11509ms
Average of 1000000 ops over 10 runs: 11524ms
[code]....
Konrad's approach to generate IL code to access the Parse method and store the call into a delegate:
1000000 ops: 352ms
Average of 1000000 ops over 10 runs: 316ms
Average of 1000000 ops over 10 runs: 315ms
[code]....
peenut's approach of using a delegate to access the Parse method directly:
1000000 ops: 272ms
Average of 1000000 ops over 10 runs: 272ms
Average of 1000000 ops over 10 runs: 275ms
[code]....
Comparatively, peenut's approach is almost 200ms faster when executed 1,000,000 times in a tight loop, so his approach wins out. Although, Konrad's wasn't far behind and is itself a fascinating study of things like ILGenerator.
VS 2008 Convert Access Database Null Values To String Type?
Jun 7, 2011i am working in windows appl vb.net 08. And i am working in Access DataBase.I have one Table Called "Person" . In this "Person" Table one Column Name Called "OtherName". In this Column binded in one of the Combobox in a Form.But the Problem is "OtherName" Column having the Null Values.Before i bind this Column to Combobox i want to convert this NULL Values to String. Why i need the values in STRING means , In my code i using this Combobox as a filter in SQL Query.If i didn`t change the Null Value to STRING , The Combobox SelectedText or SelectedValue is Showing Nothing. So i am not able to get the Record.
Whn i write a Sql Query to Combobox and apply filter in WHERE statement like Combobox.Selectedtext or Combobox.SelectedValue In "Selected Change Committed Event" then i should get the record in the Output right but unfortunatly i am not getting the Record. The Record Count in DebugPrint showing 0.
[Code]...
Value Of Type 'System.Func(Of String, String)' Cannot Be Converted To 'System.Convert
Feb 17, 2011Value of type 'System.Func(Of String, String)' cannot be converted to 'System.Converter(Of String, String)
Why? They are both effectively a function pointer (or delegate?) to a function that accept a string and return a string.
Error "debugger Cannot Convert Data Type From String To Double"
May 7, 2012I am using two textBox's. The first to enter the data. The second to convert to answer the program complies with no error, the debugger cannot convert data type from string to double.
[Code]....
why does the program not convert the textbox txtFahrenheit from string to double?
Explicit Conversion - Convert The Variable D From Double Type To Integer Type And Store The Result As 132
Oct 22, 2009I want to use explicit conversion (CType function in VB.NET) to convert the variable d from double type to integer type and store the result as 132.
Imports System.Console
Module Module1
Sub Main()
[CODE]...
This is my code. But Visual Basic tells me an error: Error1Type 'i' is not defined.C:\Users\mihaispr\Desktop\Conversie explicita\Conversie explicita\Module1.vb1922Conversie explicita
Convert Anonymous Type To Strong Type For Grouping Query?
Aug 30, 2010I've pieced together some information from other posts but I'm stuck. The first part works fine. Basically I query the database using LINQ and then I loop through the results generating a report.
[Code]...
Convert A Simple Html File Into Pdf Using ITextSharp?
Mar 1, 2011I am trying to convert a simple html file into pdf using iTextSharp, But it is not working. I am getting error :
Cannot implicitly convert type 'System.Collections.ArrayList' to 'System.Collections.Generic.List<iTextSharp.text.IElement>
d
private void Form1_Load(object sender, EventArgs e)
[Code].....
Program Designed To Convert A Simple JPG Other Image Formats?
Mar 15, 2009Simple program designed to convert a simple JPG (or possibly other image formats, BMP, TIF, Et Cetera) to text.
View 5 Replies.net - Simple Iteration Through An Integer-type Enum?
Apr 30, 2009I have the following Enum:
Public Enum myEnum As Integer
first = &H1
second = &H2
[Code].....
Obviously I can code around this issue, but I can see a scenario where that workaround could be easily missed in maintenance programming, and I'm hoping someone can recommend a simple solution that won't break if, for example, the values in the enum have to change at a later date.
Creating A Simple Leaderboard Type Application?
Apr 14, 2011I have moderate experience with VB, and am using 4.0 framework with VS 2010 pro.get a specific way i should accomplish a leader board system where it can manually assign points to players and sort them accordingly.
View 1 RepliesMake A Simple Program To Convert Ascii In Its Code Format?
Jan 11, 2010I am trying to make a simple program to convert ascii in its code format
Example: Chr(53) & Chr(53) & Chr(54) & Chr(100) & Chr(52)
to a readable format. I understand that this can be easily accomplished by writing in the ascii code into the code will do it but I am trying to create a more interactive method of doing it so I can copy and paste a long length of code into a textbox and have it update a label with the conversion.
Populate An Simple Integer Array With Variable Of The Same Type?
Aug 9, 2012I know vb.net does not include pointers like C language. but I am trying do populate an simple integer array with variable of the same type for example :
dim variable1 as integer = -1
dim variable2 as integer = -1
dim intArray() as integer = {variable1,variable2}
[code]....
it is a very simplyfied verson of what I want to do.I want to change the value of ma variables with my array referencing them with an index as if my variables were pointers of integer in c++ for example so that normally after the example, both variable should hold the number 3 instead of the number -1?
VS 2008 Ridiculously Simple Double Data Type?
Aug 20, 2009Ok, I'm half convinced that this is such a simple question that no one has ever needed to ask it in the history of google.I have a double datatype, which contains a currency value. This is returned by an API, so I can't just change it to decimal.The variable gets populated with this: 5.37979542325911E-315, which I took to mean that the current balance was $5.3797. This is incorrect!
So my question to you guys is: How do I convert a double to a data type I can use for currency?
Note: Cdec() and other casting to decimals hasn't workd. It's set the decimal to 0D.
Conversion From Type 'String' To Type 'String' Is Not Valid
Dec 21, 2009I'm in the process of porting an old excel addin that was writen in VBA to VB .NET. The Excel addin interacts with a number of external com objects. The code sorta looks like this:[code...]
What I'm trying to do is read the string from the COM object and get it in durr for use later in my program.
That second line results in the exception posted above. If I try casting with CStr/CType I get the same exception.
The visual studio watch window reports the type of hurr.getString as a "System.__ComObject" whereas the VBA watch window reports the type as "Variant/Object/String".
Microsoft.VisualBasic.Information.TypeName(hurr.getString) says the type is "String".
String Split - Error Value Of Type '1-dimensional Array Of String' Cannot Be Converted To 'String'
Mar 11, 2010my code is :
[Code]...
The error is Value of type '1-dimensional array of string' cannot be converted to 'String'.
DB/Reporting :: Conversion From Type DBnull To Type String Is Not Valid When Inserting A Record
Mar 22, 2010I'm trying to add a new record to my database but i keep getting the message - "conversion from type DBnull to type string is not valid". I think its something to do with the Employee ID when VB attempts to save it to the database my code is below
Imports System.Data.OleDb
Public Class Add
Private Sub DisplayRow()
[Code]....
Error: Microsoft.VisualBasic: Conversion From Type 'DataRowView' To Type 'String' Is Not Valid
May 25, 2011I now have SQL Parameters set up and I'm using them to save/delete/add my data. This all works well, except when it's trying to save a combobox to the datatable it appears with the error above.Majority of my comboboxes have datasources, and the valuemembers of these are the actual list items, not the ID's of the list items.I'm not sure why this error could be happening, I'm fairly sure I've connected everything to the binding source correctly; I've checked it a few times.Does anybody know what the cause of this could be? I've looked around a bit and I haven't found much
View 7 RepliesUnable To Cast Object Of Type 'ADODB.InternalField' To Type 'System.String
Apr 19, 2010I had write code (just for learning), the codes :
dim Temp as string
Temp = Recordset("
Table_Field")
but, when I start Debugging the error messages "Unable to cast object of type 'ADODB.InternalField' to type 'System.String"
Unable To Cast Object Of Type 'System.String' To Type 'ADODB.Connection'
Mar 19, 2009I'm new to VB 2005, the code below is actualy coded from VB 6 and just converted it to VB 2005. I'm having trouble with line that's on bold letters.In VB 6 this works just ok. By the way the error message is "Unable to cast object of type 'System.String' to type 'ADODB.Connection'." [code]
View 5 RepliesIDE :: System.InvalidCastException: Conversion From Type 'DBNull' To Type 'String' Is Not Valid
May 16, 2007I have these errors when creating my website?
Error 1Server Error in '/ Application. -------------------------------------------------------------------------------- Conversion from type 'DBNull' to type 'String' is not valid. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.InvalidCastException: Conversion from type 'DBNull' to type 'String' is not valid. Source Error: Line 64:
Line 65:
VS 2008 : Error: Conversion From Type 'DBNull' To Type 'String' Is Not Valid
Jun 15, 2009how can I solve this error without having to fill all of my fields. Some of the fields in my database are Nulls and some have records.
Error: Conversion from type 'DBNull' to type 'String' is not valid.
Asp.net - No Mapping Exists From Object Type System.String[] To A Known Managed Provider Native Type?
Jan 27, 2012I am getting this error No mapping exists from object type System.String[] to a known managed provider native type.The code is
Dim conn1 As SqlConnection
conn1 = New SqlConnection("Data Source=win2008-2;Initial Catalog=h1tm11;User ID=sa;Password=#1cub3123*;Persist Security Info=True;")
' Dim conn1 As String = ConfigurationManager _ .ConnectionStrings("Connectionstring").ConnectionString()
'conn1.ConnectionString = ConfigurationManager.ConnectionStrings("Data Source=win2008-2;Initial Catalog=h1tm11;User ID=sa;
[code].....
the error occurs at adapter.Fill(table)
Dim addressstring1 As String = txtpostcode.Value.Trim()
Dim addressstring() As String = Split("addressstring1", ",", 1)
Error : Conversion From Type 'DataGridViewTextBoxCell' To Type 'String' Is Not Valid
May 2, 2010I am getting the error "Conversion from type 'DataGridViewTextBoxCell' to type 'String' is not valid." When trying to display a cell from DGV in a listbox.I have my variable for the cell reference as follows:
Dim a As Object
a = DataGridView1(4,1)
To insert it in the listbox as follows:
lstLetter.Items.Add(String.Format(a))
I tried:
lstLetter.Items.Add(a)
This will not actually display the entry inside the referenced cell, it shows this in my listbox instead:
DataGridView TextBoxCell { ColumnIndex=4, RowIndex=1 }
how I need to convert this to display.
