Fahrenheit To Celsius - Conversion From String "" To Type 'Single' Is Not Valid?
Feb 20, 2012
I have already completed most of the program and it works, except when there is no input in the Fahrenhiet or is left blank.I get the following exception: on this code: Inputsingle = CSng(TextBox1.Text).Conversion from string "" to type 'Single' is not valid.Here is my code:
'Project" Convert Tempertures
'Progammer: Cathy R. Hjelm
'Description: Convert Fahrenheit temperture to Centigrade Temperature using a convert button and output Text Box[code]....
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Mar 28, 2011
I've been looking at this code for about 3 days now and I can't seem to get what I did wrong. When I run it as a console application I get "0 : 32" a lot of times.
The purpose of this code is to start at 0 degrees Celsius and work our way up to 100 by 10's. IE:
0 degrees C = 32 degrees F
10 degrees C = 50 degrees F
etc.. too
100 degrees C = 212 degrees F
Module Module1
Sub Main()
'Program: Celsius to Fahrenheit Conversion
'Programmer: T
[CODE]...
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Dec 10, 2009
Why am I getting that error message? This is the code which it's happening to:
Public Class frmford
Dim LoanAmount, InitialPrice, Make, TradeIn, OriginationFee, DepositAmount, Model, Options, AirConditioningTax, GST, PST, Total, Subtotal, APR, Months, RoofRack, SunRoof, SideAirBags, TintedGlass, RearSpoiler, GPS, PowerLocks, FreightAndPDI,
[Code]....
I tried to Dim those variables as double and it didn't work either.
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Apr 8, 2009
a user will enter a number, n, which ranges from 1 to 30. they will also enter a "P" or an "S" (sum or product). depending on which was selected, it will calculate the sum or product of the numbers from 1 to n.i'm having a conversion error on line 5 stating "Conversion from string "S" to type 'Double' is not valid." [code]
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Feb 1, 2011
This is what i have i need for it to run and ask for celsius instead of fahrenheit but it is not doing it..
[code]...
I am not understand this at all i am suppose also ask users to input a celsius degree for this part.its telling me i nedd to change formula to calculate the fahrenheit temp for this part.
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Jan 31, 2011
I am not quite understanding I am working with Microsoft Visual basic .Net programming and I Have this so far
Sub Main()
Dim fahrenheit, celsius As Double
Console.WriteLine("Enter a value for fahrenheit tempature:")
[code].....
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Mar 27, 2012
I've got this far with my interface and layout and buttons. I cannot figure out to do the functions for converting to and from celsius and fahrenheit.[code]...
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Apr 2, 2011
I've figured out the Variable declaration and coding to make it work:
Dim Celsius, Fahrenheit As Double
Try
Celsius = CDbl(txtCelsius.Text)
[Code]....
I'm gettting an "error": Option strict on dissallows implicit conversions from string to double? I have a textbox for celsius input that I want stored and converted into a label with the Convert Button Click Event.
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Mar 22, 2010
I'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]....
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May 25, 2011
I 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
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May 16, 2007
I 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:
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Jun 15, 2009
how 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.
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Mar 28, 2010
I am creating a program that will convert Celsius to Fahrenheit and visa versa. The program must use a function to return the answer. I'm using a string function that will return either the temperature in Celsius or Fahrenheit or "Please enter a valid temperature" if anything but a number is entered. TryParse is used to check if the input is valid.
When using the TryParse method in the function I am trying to use a parameter to pass the variable that will store the converted data type value [Code] The line " If Double.TryParse(tempTextBox.Text, scale) Then " is supposed to check if the conversion is possible and if it is pass either F or C as a variable to the scale parameter. It seems to verify the conversion all right but it doesn't actually do the conversion. Why isn't doing the conversion? Both F and C remain 0. I can get it to work by using two more TryParse methods (one in each branch of the If else statement in the function), but I'd rather not do this.
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May 2, 2010
I 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.
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Jul 29, 2011
I was tried to get quantity from db make use of the selection in list box. I got answered with listbox1. If i selected the item in listbox1 the quantity would appear in textbox1. But in this same code will not work for listbox2 with textbox4.. Here i given the code...
$Con.open()
$Dim cd as new oledb.oledbcommand("Select Quantity from tlist where tool_name"& "'"listbox2.selecteditem & "'" & "", con)
[Code]....
Here i got the error as "Conversion from type DBNull to type string is not valid"
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Dec 13, 2010
I've been getting this error when pulling data from a recordset. It is coming from a null entry and as a newbie to VB2008 I'm not sure how to get around this.
here is my code lblShipping.Text = reader("CARRIERCODE")
the error:Conversion from type 'DBNull' to type 'String' is not valid. Basically what i'm attempting to accomplish is to see if there is anything in that field. If so put it into the text box if not leave it blank.
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Jul 9, 2009
We get this error: Conversion from type 'InternalField' to type 'String' is not valid. When we get to this in our Dim fname2 = fname args.Graphics.DrawString(fname2, New Font("arial", 8), Brushes.Black, 5, 5) fname is a nvarchar variable from a recordset. It's just a name.
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Jan 20, 2010
I use following codes to retrieve data from table, but get error Conversion from type 'DBNull' to type 'String' is not valid.
str = "Select * from gpass where vou_no= " & Val(Me.txtGat.Text) & " And Date = '" & Me.txtDat.Text & "'"
dt = GetTable(str)
If (dt.Rows.Count > 0) Then
[code]....
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Apr 29, 2009
I am importing an Excel spreadsheet, turning it into a dataset and inserting the results into SQL Server (only 100 rows).
I am having an issue with one of the date columns in Excel, which can have a value or not. The "F" column is the one that may be blank and this is the error I get: Conversion from type 'DBNull' to type 'String' is not valid.
How can I add a check to the Dim F As Date = CDate(row(5)) to handle a null?
VB
' The use of letters instead of
' more descriptive variables is
' strictly for this sample peice
[Code].....
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May 1, 2012
I get the error: Conversion from type 'FileInfo' to type 'String' is not valid. This happens in between try and end try
Private Sub CopyNotes()
Dim NotesBase As String
Dim NotesTgt As String
[Code].....
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Aug 30, 2011
I have the following code to use Words spellcheck feature on a RTB. Once you pick the correct word in the spellcheck box and press change I get the error on th efollwoing line
strResult = Left(objDoc.Content, Len(objDoc.Content) - 1)
I tried to use CType() but still complains.
If (Len(t.Text) = 0) Then
'nahhhhhhhhhhh
Else
[Code]....
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Aug 19, 2009
At run time my application gives an error of "Conversion from type "DBNull" to type "String" is not valid. In my form only one field - Add_info is an optional field which might be filled or not by the user. Before, I had an error when an apostrophe was used so i updated the code as highlighted below. This in return removed the apostrophe error but generated an error whenever there is an empty additional field. [code]
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Aug 9, 2011
i encounter this error while passing a string as datatable.
I populate combobox1 with tables/sheets from excel and each table has datarows which i want to get the data and import to sql corresponding table, so, I declare
Dim XLSTableName as String = Combobox1.SelectedItem
And I encounter the this error : Conversion from type 'DataTable' to type 'String' is not valid
how do i return the combobox1.SelectedItem as Datatable cos if i declare
Dim XLSTableName as DataTable and pass it to the select Command thus:
Dim objCmdSelect As New OleDbCommand("SELECT * FROM [" & XLSTableName & "], ODBConn)
to obtain the dataRows I got the following error: operator '&' is not defined for types 'String' and System.Data.DataTable'
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Jul 19, 2010
I am getting the above error msg with [code]...
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Feb 22, 2012
Im trying to check a specific item if its already expired. And for some reason, im getting this error "Conversion from type 'DBNull' to type 'String' is not valid."
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Jan 7, 2009
i got following error while i am running my program here is the code scratch where i got an exception :
Try
Dim de As New DirectoryEntry("LDAP://xxx/dc=xxx,dc=com", "aaa", "secret")
Dim MyAttributes As PropertyCollection
Dim MyAttributeName As String
Dim myValue As String
[Code]...
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Dec 12, 2011
I am pulling records from an access database onto my form and have a "Next" button to get to the next record, but every time it gets to the 5th record, the error msg, "Conversion from type DBNull to type String is not valid." because one of the text boxes (fields) from the database is empty.
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Feb 10, 2010
I'm using the following code to assign record fields to variable:
Dim IPAddress As String = dt.Rows(i)("IPAddress")
Unfortunartely if the field is empty in the row i get the following error:
Conversion from type 'DBNull' to type 'String' is not valid.How can I get around this error?
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Feb 28, 2012
i have a text box and i want to insert the textbox value to my sql procedure in server and then generate record in the datagrid view ... the parameter in sql server i declare as varchar and actua database column item datatype is nchar.. anyway in what suitable datatype that i have to put in my visual basic for the textbox in order to transfer the vlaue to sql procedure and generate result
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Mar 4, 2009
I have this program i have to do for my Intro class. The assignment is to have the user enter a pay code(A,B or C) and the amount of hours worked. If the hours is more than 40hrs, they will receive time 1/2. And it must also calculate a 22% Tax.I was getting this error: Conversion from string to type 'double' is not valid. But some how i eliminated it.[code]
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