When Is It Necessary To Convert Data Types
Feb 25, 2011
Visual Basic 2010 (Express). If I take a string from a textbox and assign it to an integer variable, I'm under the impression that you're supposed to use CInt to explicitly convert the contents to an integer.intMyCount = CInt(txtUserInput.Text)However, if I don't do that, it still seems to work. Similarly, if I have an integer and concatenate it into a label's text property, it still works: lblResults.Text = intMyCount & " number of times."
rather than using intMyCount.ToString.Why does it work? Is VB doing implicit conversions when possible? Are there examples where not explicitly converting with .ToString or using CInt would cause unexpected results?
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Mar 16, 2012
In VB.NET I would like to create a complicated data structure with multiple types of data stored in an array like format (see below). I am trying to create a data structure that would look something like this: [Name; xLoc; yLoc; zLoc; [Jagged Array]] Note: Name needs to be dimensioned as a string, xLoc and so forth as integers. The Jagged Array would look like this:
[Code]...
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Aug 7, 2010
SQL Server has a Data Type of "Float". Visual Studio has a Data Type of "Decimal". In other words, if I have a variable in a VB.Net app that is defined as a "Decimal" ...can I move that value into a SQL Server Data Table column defined as a "Float"?
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Jun 1, 2011
I have been trying for days now how to create a process to the user to easily create a connection to any installed data types they have installed. I have found an example right inside vb2008. I never use this because I code my own connections, but this would be real nice if I could include it or duplicate it.
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Mar 26, 2011
I'm trying to call a C++ DLL from inside VB.NET and am having difficulty with the data types (I think), I understand VB.NET far more than I do C++...I think my main problem is differing data types and I don't understand enough C++?In C++ the DLL is called (I don't have the source for the DLL which would solve my problem, I only have a sample project written in C++) by this;
_InitSensor = (InitSensor)GetProcAddress(m_hInstLibrary, "InitSensor");
_FreeSensor = (FreeSensor)GetProcAddress(m_hInstLibrary, "FreeSensor");
_ReadTEMPsh10 = (ReadTEMPsh10)GetProcAddress(m_hInstLibrary, "ReadTEMPsh10");
_ReadType=(ReadType)GetProcAddress(m_hInstLibrary,"ReadType");
(Variables Declared Previously in other file like this;)
typedef char* (*InitSensor)(char ICType);
typedef void (*FreeSensor)();
typedef double* (*ReadTEMPsh10)(BYTE n);
typedef double (*ReadType)(BYTE address);
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Feb 25, 2010
I use Philip's MfRc500.dll for communicating with RFID chips. It contains a function for reading data, which is defined like this:[code]The second parameter in function Mf500PiccRead can returns "16 byte data block", so my long data type is too small. If I use byte() instead of long, then i get ExecutionEngineException Exception.
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Jul 14, 2010
I'm torn between using UniqueIdentifiers(UID) or some other field as my primary key for my new web app. I have two tables. I need to be able to find the UID on one record in Table1 and put that UID in a new record in Table2. I also need to be able to create a brand new UID for the new record in Table2 on the fly.
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Dec 25, 2009
I am trying to wrap a c++ dll and can use system.runtime.interopservices.dllimport and declare function to call functions from the dll. But how do i wrap the data types and everything else?
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Oct 12, 2010
I want to compare two objects whose type may be diffrent.
For eg, I expects 'true' for comparing 1000.0(Decimal) with 1000(Double) . Similary, it should return true if I compare 10(string) and 10(double) .
I tried to compare using Object.Equals() , but it did NOT work.It return false if two objects have different data types.
Dim oldVal As Object ' assgin some value
Dim newVal As Object 'assgin some value
If Not Object.Equals(oldVal,newVal) Then
[Code]....
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Oct 12, 2009
I am create a mysql table with TIME data type Field. And then store time type data into that field. But can't view in datagridview ( not show in other controls, like LABEL,TEXT,LISTBOX etcc..) . Using method is:
(LEAVEFROM TIME DATA TYPE, LEAVETO TIME DATA TYPE)
Dim cmd As New MySqlCommand
Dim adapter As New MySqlDataAdapter
Dim table As New DataTable
[code]....
Run time display error:ArgumentException was unhandled Argument 'Prompt' cannot be converted to type 'String'
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Mar 31, 2011
I have a table that has a "date" column and an "amount" column. I also have a form with two DateTimePickers ("dtp1" and "dtp2"), a button and a label. The label should show the total amount calculated from the rows whose "date" value is between the dates picked by the user with the DateTimePicker controls.
I keep getting an error with my SQL statement, and I don't know what to try. My code is as follows:
Private Sub getData(ByRef total As Double)
Dim connection As OleDbConnection
connection = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\proyectogestion.mdb")
[Code]....
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Aug 11, 2011
in Delphi I have:
type osVer = (
osVerUnknown,
osVerWin95,
[code]....
I need to translate to VB...
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Sep 7, 2010
I tend to use
If Not IsDBNull(dr("data")) Then
myData = dr("data")
End If
to catch nulls. Is there a better way? It seems I use this over and over again? Anyone write a function to check this something like
mydata = IfNotNull("data")
I don't know how to handle the different data types that could be returned.
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Mar 3, 2010
I never thought I'd say this, but I am getting pissed at how easy it is to just plop down a variable in python without any declaration. I have an existing python script which interfaces with a server, and it builds its own messages to be communicated via sockets. What I am trying to do is take the command line python script and convert it into a VB GUI app that is more user friendly.
[Code]...
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Jun 2, 2011
I'm creating a VB.Net Windows Form Application. Apologies if this is not clear as I'm still new to .Net. This consists of a text box and a gridview.The user is able to write SQL code in the textbox, click run and see the results in the gridview.It uses a SQL DataAdapter and the fill method to a datatable to populate the gridview.My problem is that I need to know the SQL datatypes for each column in the data table (NOT the .net ones). I.E SQL Server 2008 data type 'Date' is stored as System.Datetime in the datatable. I need to know if the SQL Server datatype is 'Date' or 'Datetime'.
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Nov 1, 2009
I have a class with a Property called 'Value' which is of type Object.Value can be of any type, a structure, a class, an array, IList etc.My problem is with the setter and determining whether the value has changed or not.This is simple enough for value types, but reference types and lists present a problem.For a class, would you assume that the Equals method has been implemented correctly, or just assume that the value has changed every time the setter is called?If I did assume it's changed, then perhaps I should assume it for value types as well, so that the behaviour is consistent.
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Jul 26, 2011
I have a value of: "2.54334881002458E-37" and i keep getting "overflow" exception when i'm using a double.what should i use to make this work?
code snippet:
Dim curries, act, cat As Double
For Each dataRow As DataRow In dt.Rows
curries = dataRow("Activity")
getting the error when i try to assign Activity to curries.but "activity" is a string in the database....
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Dec 8, 2011
I define 3 arrays: ID(n), Hour(n), Showed(n). If Hour(i) = actual time, I get the data pointed by ID(i), if not Showed(i).
BUT... I can add new hours or modify some existent, but I need to have the Hour array sorted. If I sort this array, the ID and Showed will point to different data.
So I though some different solutions:
1 - To make a string array with all inside (a 7 characters ID, a 5 characters Hour and 1 char for showed (T or F)). It could work, but, how can I sort the middle part of the array (Hour)? So, this don't work.
2 - A 3 dimensions "multitype" matrix (1 dimension of type Integer, the second of type Date and the third of type Boolean). I have no idea about how this can be done.
3 - A 3 dimensions string matrix, some like the "all inside" array: ID converted to a fixed size string, hour converted to a 5 chars string (hh:mm) and Showed converted to T or F. And sort the second dimension.
4 - Sell my copy of Visual Studio and drive a taxi cab
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May 30, 2011
How to create a class which inherits from a data type, specifically from Char data type? I just want to add one property to it. If it's not possible, are there any other ways to accomplish this?
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Jun 30, 2011
I want to have data types name inside enum as given below
Enum FieldTypes
String = 0
Boolean = 1
Date = 2
End Enum
Is there any method to achieve this?
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Jun 6, 2009
I would like to populate a Combo with all the type names that a DataColumn can be ("System.String", "System.Boolean", etc). How can I do that without having to manually add the combo items?
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Oct 27, 2009
I have a question (suppose to be simple). The question related to reading text file which is in the below format.
[Code]....
What I want here is to store the first data column in the file to be stored in AreasString and 2nd column in Level, 3rd in Importance and so on untill the end of the data. In addition, How can I check the type of data? For example, if I want to say: If 10.25 is double then msgbox ("it is double") else msgbox ("it is integer")
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Sep 29, 2010
I freely admit that I tend to avoid using API calls as much as possible I wish to use this API call
[Code]...
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May 7, 2011
I'm having a bit of an issue with this program I have been working on for my class. It's a future values calculator, that takes a single data type, decimal data type and a integer data type does the formula and then spits back out the Future value. What i'm having difficulty with is converting the string over.
Public Class Form1
'Define the Module level variables
Dim FutureValueInteger As Integer
[Code]....
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May 5, 2011
I am looking to define data types by fields in SQL Server 2005. My source is an Excel spreadsheet and I cannot define by columns because each row requires a set of definitions applied to each field in that row. Ex, row 1 requires field1 to be CHAR while in row 2 field 1 needs to be DATE.
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Jan 19, 2012
addressing the need for getting the bytes of an object. But I am wondering if there is an approach to calling BitConverter.GetBytes on a generic type where I know the type is a primitive (Int32, UInt16, etc).
Public Sub Foobar(Of T as Structure)()
Dim x as T 'Assume T is declared as Int32
Dim y() as Byte
y = System.BitConverter.GetBytes(x)
End Sub
The above will throw your usual error:
Overload resolution failed because no accessible 'GetBytes' can be called with these arguments:
'Public Shared Function GetBytes(value As Double) As Byte()': Value of type 'T' cannot be converted to 'Double'.
'Public Shared Function GetBytes(value As Single) As Byte()': Value of type 'T' cannot be converted to 'Single'.
[code]....
One solution I think would work is a large Select Case calling GetType(), but that is horrendously slow (because of boxing) and looks ugly. I would think that since I call my higher level class with a primitive data type for T, that the compiler would be smart enough to figure it out, but I assume I am not providing enough information for it to derive what T's underlying value is at compile time for the invoked instances.
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Sep 16, 2010
Does anyone have a list of OleDBTypes and how they match up with MS Access and SQL Server Data types. I would like this to be able to better write code for my parameter collections. Plus when looking at all the options availible with intellisense when programming in vb2008 v.s. SQL datatypes, there are some not so obvious choices.Here is the list I get from VB2008 using Intellisense:
OleDb.OleDbType.BigInt
OleDb.OleDbType.Binary
OleDb.OleDbType.Boolean
[code]....
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Jul 9, 2009
I have this sql statement:
CREATE TABLE [dbo].[User]( [UserId] [int] IDENTITY(1,1) NOT NULL,
[FirstName] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL, [MiddleName]
[varchar](50) COLLATE SQL_Latin1_General_CP1_CI_A
What I want is regex code which I can use to get all fields and data type. So will return something like that:
FirstName varchar
MiddleName varchar
The sql statement will always have this format. I am using .Net to run this regex
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Mar 13, 2010
I have a jagged array.
vb
Dim jaggedarray(numColumns)()
Does this accept multiple data types?
I'm trying to get the results of a SELECT SQL query from Data.OleDb.OleDbDataReader.Item Are there any better ways of approaching this?
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Jun 8, 2010
This should be an easy one, looks like I got myself too confused.I get a table from a database, data ranges from varchar to int to Null values. Cheap and dirty way of converting this into a tab-delimited file that I already have is this (shrunken to preserve space, ugliness is kept on par with original):
da.Fill(dt)
' da - DataAdapter '
' dt - DataTable '
[code].....
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