Validate User Input - Loop Conditional Statements To Indicate Errors?
Mar 20, 2011
I have several text boxes I need to validate. I am not understanding how to validate in Visual Basic 2008. So I deployed standard If Statements to handle bad data. I am having two problems.
Lets say the user entered wrong data, example, numbers; an error message is displayed. The text boxes cannot contain numbers, be left empty or contained characters, like !@#$. The problem is if the user enter text, and then entered a wrong data again the code does not work or display error message. How can I make the conditions so that they throw out error message even if the user had previously entered good data.
Another example: If the user enter good data in text box 1 and bad data in text box 2, the error message does not work.
Finally, how do I filter out characters to allow only text. Is there a way to use this code on multiple text boxes with out writing the entire code for each form control?
Here are the conditional statements.
Private Sub btnDataSubmit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDataSubmit.Click
If IsNumeric(txtDataEntry.Text) Then
lblErrorDisplay.Text = "Invalid Name!"
lblErrorDisplay.BackColor = Color.Red
[Code] .....
I am trying to create a new class to validate user input and then call that class from my main form. I am not looking for anything to do the work for me, as this is the last part of my project but I am looking for a place to start. I tried the isNumeric IF statement but I have to create an object to reference the specific text box. Can I be generic and say that aTextBox requires validation and then call that class?
I have created a for loop the validates a user account. however whenever i hit the button that starts he code it won't let me allow user input. I have checked a forums and other sites and its bugging me. i know its small but i don't know what i need to be doing to get out of the loop
I am making a windows application that should validate user input before opening up the next form page. I can get the error messages to show, but after correcting the error, they won't disappear and open up the form.
Option Strict On Public Class Form1 Private Sub btnDistance_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDistance.Click 'The btnEnterSpeed click event accepts and displays up to ten speeds from the user'and then calculates and displays average speed
[Code]...
I cannot figure out how to incorporate the number of days into the input box then get it to loop and count the number of times the User inputs in the number of days. Then I have to incorporate it into the equation to get the total distance D = MPH * Hours. What I have right now wil not count up the number of days and locks up after I input one number and will not add anything to the listbox. Because I also have to make sure that they cant add nonnumaric values and the number of hours per day cannot exceed 20. I have put things in and taken them out but it has been 2 days and I am lost now
I need to take user input, validate to ensure there's no negative numbers and display monthly fee and check fee in a Label.....with a calculate button_Click
how do I handle the errors that may appear from the user of my program. For example, I have an triangle area program in wich I ask the user of the program to insert the length of the base and height of the triangle in a textbox. But what if he inserts a letter or something else, like a sign....my program will crash...
I know that one method would be to use On Error GoTo but I don't know how. If maybe you can direct me to some link or you could explain how do I handle errors, I would be grateful. Maybe you can even show me other ways to avoid errors from the user input.
This is my small program so far:
Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click Dim , Height, ARIA As Integer
Coming from PHP and more specifically many of the MVC frameworks out their, I've been use to using basic foreach and if constructs in PHP directly in the layout. Now that I'm learning ASP.NET I'm presented with more proprietary concepts like a ListView to control looping, etc...
So to give an example of what I want to do..
<div id="container"> <h1 class="header">Title</h1> <% For Each item In ItemsCollection %>
[Code].....
Then there isn't a lot I have to handle in the Code Behind file... besides making ItemsCollection available.
Is This considered Bad Practice? Should I spend the time learning the proprietary controls for ASP.NET? Are there specific limitations of this approach?
Is there a way to define a conditional define, i.e. #const, in a asp/vb.net app that it accessible across multiple source files? I want to use, for example, #const useOracle=TRUE but to be able to change it's value in only one place.
VB.NET 2008 windows app form.I have a groupbox with several checkboxes, comboboxes, and textboxes within it.With the help of StackOverFlow members, I've learned how to use the FOR/NEXT loop to find all checkboxes that are checked.[code]As you can see by the code sb.tostring will print every checked checkbox name on its own line.How do I associate the proper combobox.selecteditem, textbox.value, and checkbox name to print out on the same line.When I say proper...example; checkbox=pen, combobox=color, textbox=quantity.Let's say my other checkboxes are different items and the rest of the boxes are the same.
I wrote simple update/insert statements that are returning a syntax error, what am I missing? The table name is notes, the field note is type memo, acaps is a double. update notes set note='why is there a syntax error' where acaps=12345
I need an additional loop argument within an If statement that resides in a very large do...loop block. It will speed the application considerably if I can have the do...loop block loop prematurely. I already have the remaining code after the additional loop argument in a large if...elseif block to achieve the result, but making it simply loop instead of going through this would speed the application.
I have a piece of code that loops through the rows in a database and brings out information.
The code is attached to a button(search). To search for data, you enter a phone number, the loop goes through the data rows and bring out the information is it is there.
Everything works great accept I have added a second table to the database.
So do I add a whole new loop statement? Example lets say I had a new data row, how can I add that to this statement so that both tables are searched?
This is the code:
Dim strGetRecord As String = masTxtPhoneField.Text For validData = 0 To storedtData.Rows.Count - 1 If strGetRecord = storedData.Rows(validData)("fldphone").ToString Then
I am using Visual Studio .Net 2008. I am using "Structure" statement for my work. It is working with me perfectly. I am not sure if Understand the structure statement very well because it does give me wrong answer if I change the position of "Redim" of the structure elements. My problem is the structure is using "Redim" in many places which is a dangerous procedure. I do not know how exactly to explain my problem because the structure in my code is used widely and called in many subroutines. I will try to explain with the below simple code:
[code]...
My question is: How can I move the all "Redim" statements outside the loop so that the Redim happens only ones? What does "TheCollection(Iteration + NumberOfMembers).TheResult" does take? Is it zero or what?I searched the web but I could not find a proper website or article which explains the structure. The only useful link I found is this:[url]
how one would go about validating input into a textbox for example:
Lets say the first letter the user enters has to be 'A' and the third letter the user enters has to be any number ranging from 0-9 and the length of their input cannot exceed lets say 10.
This is what I have so far:
If txtOperatorID.TextLength > 10 Then bErrorOccured = True sErrorMessage = sErrorMessage & "-No more than 10 chars" & vbCrLf
[Code]....
The coding for the length works(is there a better way to do this)? The coding for the first letter to be A works but then I have no idea how to set validation for any proceeding characters entered. Am i right in thinking I have to find their position somehow in the string if so how?
I am going to make a form which will have 10 MaskedTextBoxes. I want to validate input of all these MaskedTextBoxes then Sum the input of validated one into another MaskedTextBox. If there is any value in any MaskedTextBox it mast be validate by the format of "9990.000" or if it is empty return zero. I do not want to write the same code for every MaskedTextBox, I want to use function & sub. The problem with "e" type TypeValidationEventArgs. When I call the SumBurBoxes sub in txtBur_1_TypeValidationCompleted & give the "e" as second parameter, then if the txtBur_1 be invalid type and any other txtBur Boxes have value it will get error on all boxes if the txtBur_1 be valid type even the the other boxes be invalid type it does not get error on them.
Here is my Code.
Public Class Entrance Private Function RetrnTxtBur(ByVal index As Integer) Dim txt(0 To 9) As MaskedTextBox txt(0) = Me.txtBur_1
Should I validate input parameters on all functions I create? Input isn't passed from a user, but from other routines as part of an automatic process.
I use error handling. I'm not sure what more validating input could do for me. If the input isn't valid, that's pretty much the same thing as an error, isn't it?
I am creating a program and I need to validate my text boxes. For the program the user needs to put in a phrase. But I am not sure how to make sure that the user actually entered in a phrase, the phrase isn't (ex.) skldkfdl, or that there isn't a space.
Im builtina an windows application based on 3 tiers model. I have BLL, DAL, and UI Class. IN DAL I have SQL code, In BLL I have proprietie and methods .Im trying to validate the input fields on BLL class and no problem,and im just do it after SET instruction. I also PUT a message to view error. But From BLL class I want to put the focus in textfield that return error. I cant acess form proprieties (the forms are on UI class).
Public Class Form1 Imports System.Math Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load[code].....
For some reason, when i try to start the program im getting the following errors: Error1'Imports' statements must precede any declarations.C:Vb10sbschap05My Framework MathMy Framework MathForm1.vb25My Framework Math
Error2'Sqrt' is not declared. It may be inaccessible due to its protection level.C:Vb10sbschap05My Framework MathMy Framework MathForm1.vb1018My Framework Math
Im using Visual Basic Express 2010.This is from a tutorial in Microsoft Visual Basic 2010 Step by Step
I have an asynchronous task that is executing a function. The function does not contains any looping statements, but instead it is executing series of sql commands on sql server. Now, i have a button on my window that can cancel these sql operations. In other words, cancel the whole asynchronous task.
I know that this technique will require CancellationTokenSource and CancellationToken to cancel the task, but i've seen many examples on the internet and all of them are showing that the function that task is executing contains loop statements in which they are checking for IsCancellationRequested boolean property. But in my case, it is not so. My function does not have any loop statements in which i can do a check on this boolean property.
I'm trying to validate input boxes for numeric value and range value. If I validate for either numeric value OR range value there is no error (for example, comment out one of the validation statements), but if both statements are present and I enter "a" I get an error "Conversion from string "a" to type 'Double' is not valid." Can anyone tell me what I'm doing wrong?
how to validate 4 textboxes so that only numbers 1 to 4 can be entered but no number can be repeated.i already have code but it only validates some of the boxes and allows numbers to be repeated in other
Public Class frmGrid Private Grid() As Short Private Const intDimension As Short = 3
i am use vb 2003 windows app with access 2003 database i want this code to check for numeric input only in the last text box CompanyProdPriceTxBx.Text
this is my
Private Sub SaveCompanyProdbtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles SaveCompanyProdbtn.Click Dim rep As Integer If CompanyProdNameTxBx.Text = "" Then rep = MsgBox("Please Input Product Name", MsgBoxStyle.Critical)
How do I validate textboxes so that they accept only numerical input (1 2 3 etc and not abc @$ etc)? Is there some kind of property of the textbox that I have to change?
