Im trying to improve some apps ive written, the first is a console app... Im trying to get it so that i wont get an invalidcastexception if the user inputs a string, when the variable is type "Double"
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I'm making a small webbrowser, and I need to make sure the user inputs a proper url!
The text box is called TextBoxAddress.
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:
I have used the Gridview_PageIndexChanging event in asp.net.i have used the code like this:
gridFileDetails.PageIndex = e.NewPageIndex
During the run time when i clicked the next page,it generates an error:
An exception of type 'System.InvalidCastException' occurred in FFK.DLL but was not handled in user
code
Additional information: Unable to cast
object of type
'System.Web.UI.WebControls.ContentPlaceHolder'
to type
'System.Web.UI.WebControls.GridViewRow'.
in the RowCommand event,I have used the following RowCommand event:
Protected Sub gridFileDetails_RowCommand(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewCommandEventArgs) Handles gridFileDetails.RowCommand
Dim row As GridViewRow = CType(CType(e.CommandSource, Control).NamingContainer, GridViewRow)
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I keep getting this error "InvalidCastException: Conversion from string to type 'Double' is not valid." whenever I try and run this piece of code. Could someone explain to me where it is trying to make a conversion to double? No matter what I do to my input string, I get the error.Here is the stack trace:
Input string was not in a correct format.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.FormatException: Input string was not in a correct format.
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So, I run a select statement in SQL and then it has something like " where clientName = 'John Doe' " I can generate a datagrid or dataset off the SQL statement, but it will only be good fro one client...... I would like to be able to populate a dataset/grid using the select satement and then having something like a combo box of names the USER can choose. Then the user selects the name and the datagrid is populated with that clients info or w/e........
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why I got the following (InvalidCastException was unhandled) on the following code and how can I solve the problem.
LabelPB.Text = P - Total.Text 'Conversion from string "" to type 'Double' is not valid
I am using .ToString("#,##0.00") to format a number. I'm sure I have used this before but today it doesn't work.I want to format a System.Double value from the datatable like this 12345.6789 to 12,345.68
Code:
myString = dt.Rows(i)("column_name").ToString("#,##0.00")
gives a System.InvalidCastException:Conversion from string "#,##0.00" to type 'Integer' is not valid.
Trying to insert a record into a db, but I get the following error System.InvalidCastException: Conversion from string "Duck" to type 'Integer' is not valid. ---> System.FormatException: Input string was not in a correct format."Duck" is what I entered into a LNameTextBox.
Here is the code.
Dim myCommand As OleDbCommand = New OleDbCommand("INSERT INTO [Info] ([UIN], [Last Name], [First Name], [Department Code]) VALUES (@UINValue, @LNameValue, @FNameValue, @DeptCodeValue)", myConnection)
myCommand.Parameters.Add("@UINValue", OleDbType.Integer, UINTextBox.Text, "[UIN]")
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I can't understand why it is trying to converty the Last Name textbox entry to an integer.
How do you validate input when you are dealing with doubles. I have successfully gotten the message box to pop up when the user enters a number in a text field, but what if I have a text box that requests a number from the user and they enter text? This is the code, the even for btnDisplayFull works fine, but not btnDisplayRqst: [code]
View 2 RepliesI have four textboxes,
I want textbox1 to accept only char data.
I want textbox2 to accept only numeric data.
I want textbox3 to accept only alphanumeric data.
I want textbox4 to accept only bolean data.
Could anyone assist me in solving my problem ? My code was written in VB (VS 2003.)I got this error: System.InvalidCastException: Cast from type 'DBNull' to type 'Integer' is not valid. in my code.Here is the code line where I am getting the error: LeadCampusID = CInt(.Item("mkCampusID"))I fixed the error by making the changes in the code as :
If Not IsDBNull(.Item("mkCampusID")) Then
LeadCampusID = CInt(.Item("mkCampusID"))
Else
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Is it possible to have a Textbox on a form that when the user inputs data, ( during Runtime )that data remains in the Textbox for good and the Textbox then becomes read only ? Is it also possible to make it so that the CD with the programme on, is in the PC when the programme is being used. Perhaps writing the Textbox data back onto the CD ?
View 1 RepliesWhat is the best method to do data validation? I want to do data validation when the user exits a control so that he gets immediate feedback. I can use the Validating event or the Leave event for that. The problem is, that if the user doesn't know the right answer, and just wants to click the cancel button and leave the form completely, it won't let him. It continues to give him an error message until he completely deletes his answer. Very frustrating. Does anyone have a good method for doing this?
View 5 RepliesWhen I read a value from text box I want to make sure user has entered a number(int/float/double etc.) not a string. Is there any function to check it? otherwise how do i validate it.
Language : VB.NET
Version : Visual Studio 2005
'Declare the price rate per night
Const decNightly_Rate As Decimal = 350D
Private Sub btnCalculateCharges_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculateCharges.Click
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I am trying to make a hospital form where the user inputs data for a hospital bill. I have to create three functions: CalcStayCharges, CalcMiscCharges, and CalcTotalCharges. I do not know why this code won't work.
I need to create a function which have either 1 parameter with a string as data type or 2 parameters with double as data type.Something like the substring method.
View 2 RepliesFollowing is my code. Private Structure DISPLAY_ELEMENT_TYPE
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Actually this is vb6 to .net converted code. I m getting compile error at following line
temp = Lset(DispElem(i)) bcz Lset is not supported in .Net Lset accept string data type for first parameter and interger for second.If you know any alternet solution or if you have any source code for Explicit convert UDT to string type and vice versa.
I have to make a basic program that: Create a program with a simple interface that
1. Asks the user type his/her email address into a textbox.
2. When the user clicks the "Evaluate Email Address" button, one of two message boxes pops up: "That is a valid email address!" with an "Information" icon, or "That is an invalid email address!" and on a second line, "Please retype your email address.", with an "Exclamation" icon
3. To be considered valid, the email address must -include an "@" symbol, and -it must end in either ".com", ".net", or ".org" or ".edu" (I don't know how to check a string and test if its last four characters end with any of these and make it say not valid email address. I think I might have to use a case statement)
The following line is giving me an InvalidCastException when trying to convert to IEnumerable type, even though I have implemented IEnumerable interface. Return New CountryInfo(CountryCodes(i), CountryNames(i)) (also in bold below)
Imports System
Imports Gaia.WebWidgets.HtmlFormatting
Imports System.Collections.Generic
Imports System.Globalization
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I have a program that calculates commission, but if the commission is nothing then I do not want it to show a zero commission. I want a message box to show a message that there is no commission earned.
View 1 RepliesI need something tje user can type in data to such a parts QTY cost etc. There are no predefined parts list so the user can enter any part name/Number and there is no limit to amount of parts that can be entered.
Does anyone have any idea what might be useful. It was thinks of a listview bu i can't see that you can type into that. I cant use comboboxs because there are no predefined list and i know there is some way to generate text at runtime (i think) but i don't know how to do it and i would prefer a clearer approach.
I am checking for empty string values, but how do i see for the Quantity text box if the user chose only numerical values after the empty string. For example...
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I'm a beginner to Visual Basic. In here I want to recreate a piggy bank which tells me how much money do I have. I created a function but the program tells me :
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I use this code to populate combobox1&2:
'Main form on load events
Private Sub frm_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
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I'm not sure the best way to accomplish this, what i have is 10 checkboxes on a form named chkbox1 to chkbox10, say ther user selects 4 then clicks a button, i was wanting to execute code one after each other like[code]...
View 3 RepliesI'm trying to create a User form that has six inputs.
1.) User input textbox 5.00 to 60.0 inches only accepted.
2.) User input textbox 2.50 to 30.0 inches only accepted.
3.) User input textbox 6, 8, & 10 nominal input only accepted.
4.) User input textbox 60% or 65% only accepted.
5.) User input textbox 2.50 to 30.0 inches only.
6.) User input textbox where 500 shows up in the box as "standard" but can be changed by user input.
Then an "OK & Cancel" button. I don't know whether to use a dialog box or a form, what class, masked text box vs. not masked, etc.
How can I prevent users inserting sql injection in my database? How can I validate their inputs? I am new with this sql injection. I don't know how to prevent users to insert this sttmnentif and I don't have the idea of sql injection how can I be sure that I am safe with sql injection??
View 1 RepliesError is Simple Application -- Error Type (A first chance exception of type 'System.InvalidCastException' occurred in Microsoft.VisualBasic.dll)
View 3 RepliesI was trying to find examples of how one would make a webpage using asp so that I could have the visitor enter information on a form and then when they hit submit it will be attached to my webpage indefintaly and any visitor can view it.
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