.net - String Value Type Or Reference Type?
Aug 11, 2010Is string a reference type or a value type?
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Similar Messages:
Value Type Versus Reference Type Memory Allocations
Jan 8, 2010I am little bit confused in value type and ref. type memory allocation.
Consider following case:
public struct Employee
{
public int Emp_no;
public string Emp_name;
};
//Createing object of struct
Employee objEmp = new Employee;
objEmp.Emp_no = 1012;
objEmp.Emp_name = "emp name";
So I have query regarding :
Q1. 'struct' is a value type and 'string' is reference type of data type. Then if I use 'objEmp.Emp_name' is stored where? The location is in heap or in stack memory? What type of this 'Emp_name' variable?
Q2. If I run garbage collection explicitly then what will happen with 'objEmp' object?
Repeater Itemdatabound Event Value Type And Reference Type?
Mar 29, 2010Im trying to bind a list with datetime objects to my repeater.
if (e.Item.ItemType == ListItemType.AlternatingItem || e.Item.ItemType == ListItemType.Item)
{
DateTime actualDate = e.Item.DataItem as DateTime;
}
When I want access the itemdatabound event on the repeater Then I get an errormessage which says that DateTime is a valuetype and not a reference type.My solution is that a wrap the datetime in a custom object (reference type) and pass that to the repeater datasource instead of the datetime. But Im wondering if there are other solutions where the repeater takes valuetypes (DateTime objects).
Forms Data Controls :: Conversion From Type 'TextBox' To Type 'String' Is Not Valid?
Sep 6, 2010I have a FormView that allows a user to register for a company event. I want to do a couple of things with this form.
1. I need to write this data to a MS SQL database
2. I need to send an email confirmation of their registration to their email.
I know how to do both of these things, but i am having trouble doing both at the same time.
It would be nice if I could do it in one click, but I coded it into two pages to try to help simplify it.
The first page allows the user to input their information into a formview and when they click the submit button, it places those answers into session variables:
[Code]....
[Code]....
The Second page confirms the users information by taking those session variables and placing them into labels:
[Code]....
[Code]....
However, after I place information into the formview on the first page, it throws up this error:
"Conversion from type 'TextBox' to type 'String' is not valid".
DataSource Controls :: The Given Value Of Type String From The Data Source Cannot Be Converted To Type Datetime
May 19, 2010I have this error "The given value of type String from the data source cannot be converted to type datetime of the specified target column." when I used sqlbulkcopy to do the transaction
Here is my code:
[code]....
MVC :: Unable To Cast Object Of Type 'System.String' To Type' / How To Fix This Error
Mar 24, 2010i am using this code for send data to view
[Code]....
Controller e 'System.Collections.Generic.IEnumerable [Code]....
by this code i am render view
[Code]....
after run the application i got this error
Unable to cast object of type 'System.String' to type 'System.Collections.Generic.IEnumerable`1[BentaAccounting.Models.Repository.AllData]'.
DataSource Controls :: 'Conversion From Type 'DBNull' To Type 'String' Is Not Valid.'
Feb 17, 2010I'm trying to get a value from a database and I'm getting an error, see code below:
[Code]....
I get and error when I'm trying to convert the value out of the stored procedure to the string SNAME. Error is as follows:
'Conversion from type 'DBNull' to type 'String' is not valid.'
and the stored procedure is as follows:
[Code]....
Forms Data Controls :: ERROR - Conversion From Type DBNull To Type String Is Not Valid?
Jan 13, 2010I have a gridview which I'm trying to get the display of phonenumbers listed in a certain display format; (xxx) xxx-xxxx.If I have the code such as this, it displays the unformatted phone number and (000) 000-0000 for the null items.
[Code]....
MVC :: Getting Error: The Parameter Conversion From Type 'System.String' To Type 'Models.Organization' Failed?
Oct 15, 2010I seem to be having issues with posting forms with DropDownLists. I've looked all over the net and tried various solutions, but none seem to work for me.
I'm getting the following error: The parameter conversion from type 'System.String' to type 'Models.Organization' failed because no type converter can convert between these types.
Here's my ViewModel:
[Code]....
Here's my controller:
[Code]....
The objects are generated by ADO.NET Entity Framework. Organizations is its own object, but also a property of Profile (each user belongs to one organization). Now I understand what the error message is saying, just not sure how else I'm supposed to do this.
ADO.NET :: How To Handle Conversion From Type DBNull To Type String Is Not Valid
Oct 5, 2010Conversion from type 'DBNull' to type 'String' is not valid
Dim OledbString As String = ("SELECT Product_Hierarchy,Model,Origin,Item_Code,Description,Price_USD FROM [sheet1$]")
'Dim eAdapter As New SqlDataAdapter(sqlString, connection)
Dim eAdapter As New OleDbDataAdapter(OledbString, connection)
Dim eTable As New DataTable()
eAdapter.Fill(eTable)
Dim i As Integer = 0
[code]...
Web Forms :: Conversion From Type DBNull To Type String Is Not Valid
Nov 18, 2012I have a web in ASP.NET AND CODE IN VB MY DATABASE IS ACCESS WHICH WAS CREATED INITIALLY AND OLD DATA IS ACCESSED FROM THIS ACCESS DATABASE.
THE PROBLEM IS WHEN THE FIELD IS BLANK THE FOLLOWING ERROR COMES
Conversion from type 'DBNull' to type 'String' is not valid.
MY CODE IS AS UNDER
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSubmit.Click
Dim PNO As String = inputtxt.Text
Dim connectString As String = "Provider=Microsoft.Jet.OLEDB.4.0;" & _
"Data Source=C:awingAWing.mdb"
Dim con As OleDbConnection = New OleDbConnection(connectString)
con.Open()
Dim qstr As String
qstr = "select * from PersData where PNO='" + inputtxt.Text + "'"
[Code] .....
Unitended Reference Comparision / Get A Value Comparison, Cast The Left Hand Side To Type 'string'?
Mar 23, 2011I am getting this warning:Possible unintended reference comparison; to get a value comparison, cast the left hand side to type 'string'I tried this:
if (Convert.ToString(Session["message"]) == SESSIONTIMEOUT)
or
if (Session["message"].ToString() == SESSIONTIMEOUT)
But I'm still getting the above message.
Forms Data Controls :: No Mapping Exists From Object Type System.String[] To A Known Managed Provider Native Type?
Dec 1, 2010I'm trying to pass email addresses from an array to a stored procedure, then display the results in my gridview. I get the following error:No mapping exists from object type System.String[] to a known managed provider native type.On this line: Dim DR As SqlDataReader = MyCommand.ExecuteReader
[Code]....
Use With A Reference Type Or Nullable Type
Sep 13, 2010Why following Code giving Nullable Error, it should converted to int right?int? abc=Session["test"] as int;t be used with a reference type or nullable type ('int' is a non-nullable value type)
View 9 RepliesForms Data Controls :: Unable To Cast Object Of Type 'System.DBNull' To Type 'System.String'.
Oct 1, 2010Basically, what I did is that: I have a table in SQL database and some of data fields allow null. I built Objectdatasource through dataset. When I built update page using dataset. It generate the following error before showing the update page correctly. It seems I have issue to retrieve the null value from the database through using objectdatasource through dataset. Any suggestions?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
View 6 RepliesDatabases :: Retrieving From OdbcDataReader / Unable To Cast Object Of Type 'System.Byte[]' To Type 'System.String'
Feb 16, 2010I have defined an ODBC Command and ODBCdatareader as follows
OdbcConnection myConnection = new OdbcConnection(connectionString);
OdbcCommand myCommand = new OdbcCommand();
myCommand.Connection = myConnection;
myCommand.CommandText = "select UOPGM from GREG.TUSROPTF";
OdbcDataReader myReader;
myConnection.Open();
myReader = myCommand.ExecuteReader();
When I try to retreive from the reader as follows:
while (myReader.Read())
{
string someString = myReader["UOPGM"];
lstNames.Items.Add(someString);
}
I get the following error
Error reading the database. Unable to cast object of type 'System.Byte[]' to type 'System.String'."
I have also tried string someString = (string)myReader["UOPGM"]; to no avail
DataSource Controls :: Unable To Cast Object Of Type 'System.DBNull' To Type 'System.String'
May 28, 2010I am trying to write a table output from SQL database to a gridview/ Data List through an Object Data Source. I am a new starter and your help will be useful.
public List<Staff> GetStaff()
cmd.CommandType =
SqlConnection con =
new
SqlConnection(connectionstring);SqlCommand cmd =
new
[code]...
Web Forms :: Unable To Cast Object Of Type 'System.DateTime' To Type 'System.String'
Nov 10, 2010[Code]....
Above is my code. The error I'm get is, Unable to cast object of type 'System.DateTime' to type 'System.String'.
The column "To" and column "Subject" are strings and column "Receive" is DateTime. I can't made any changes in the database, so I need to write some code to handle casting a string to datetime or if statement as a work around.
C# - Error - "Cannot Convert Lambda Expression To Type 'string' Because It Is Not A Delegate Type"
Jun 12, 2010I 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
Web Forms :: Unable To Cast Object Of Type System String To Type System Byte
Feb 20, 2013Unable to cast object of type 'System.String' to type 'System.Byte[]'....
on line #2
private void download(DataTable dt) { Byte[] bytes = (Byte[])dt.Rows[0]["FileData"];
Response.Buffer = true; Response.Charset = "";
ADO.NET :: Unable To Cast Object Of Type System.Guid To Type System.String?
Sep 17, 2010[Code]....
System.InvalidCastException was unhandled by user code
Message=Unable to cast object of type 'System.Guid' to type 'System.String'.
Source=System.Data.Linq
System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.Execut
WCF / ASMX :: Call HTTPS Web Reference Through Another Web Reference - An Unhandled Exception Of Type Error?
Aug 6, 2010I am trying to call web reference "A" in an application.
The web reference "A" will then call a function in another web reference "B" through HTTPS connection (require certificate).
Then I keep getting the following error:
An unhandled exception of type 'System.Web.Services.Protocols.SoapException' occurred in System.Web.Services.dll
Configuration :: MIME Type For .licx Extension/Error 53 Unable To Resolve Type ' <add Type="TabStrip" Version="7.0" />'...
Nov 12, 2010I am not sure if I have found the right forum for this one.
the problem is:
I have a .licx file in my rootfolder.
I am getting the error:
Error 53 Unable to resolve type ' <add type="TabStrip" version="7.0" />' C:inetpubwwwrootCrop_ApplicationCrop_Applicationeo_web.licx 7 Crop_Application
,which I get for all the types that are in the xml file(i just gave one of them).
A friend told me that I have to add the type .licx in the MIME type in the IIS .
The problem is that I find the MIME type, I add the extension type .licx but I do not know the MIME type for .licx
Unable To Cast Object Of Type "System.String" To Type "System.Data.DataTable"
Mar 27, 2011what is wrong with this syntax datatable temp = (DataTable)du.Rows[0]["NAME"] I get the error message Unable to cast object of type 'System.String' to type 'System.Data.DataTable'.
View 6 RepliesThe Type Or Namespace Name 'IUnityContainer'...are You Missing An Assembly Or Reference
Jan 21, 2011I recently moved my class based on IUnityResolver from the mvc3 project (where I tested it), to a class library (which references all five Unity dll's. I'm getting the following error, why? Are there other dependencies for which I am unaware?The type or namespace name 'IUnityContainer'...are you missing an assembly or reference?
View 3 Replies