Why Does Integer.TryParse Set Result To Zero On Failure
Jul 3, 2009
My understanding of the Integer.TryParse() function was that it tried to parse an integer from the passed in string and if the parse failed the result integer would remain as it did before.
I have an integer with a default value of -1 which I would like to remain at -1 if the parse fails. However the Integer.TryParse() function on failing to parse is changing this default value to zero.
Dim defaultValue As Integer = -1
Dim parseSuccess As Boolean = Integer.TryParse("", defaultValue)
Debug.Print("defaultValue {0}", defaultValue)
Debug.Print("parseSuccess {0}", parseSuccess)
The code performs correctly when the input is an integer, but when I enter a character, the result is as though I've entered an integer. Can you tell me what's wrong with my TryParse statement?
Private Sub btnCompare_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCompare.Click
this is for homework but I have 90% of the project done, I just need to finish the data validation portion of the code. This is what I have for the calculate click event:
this is for homework but I have 90% of the project done, I just need to finish the data validation portion of the code.This is what I have for the calculate click event:
Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click Dim intInputA As Integer Dim intInputB As Integer Dim intInputC As Integer
[code]....
My Problem: I am using the Try parse to validate weather the inputA(B)(C) is an integer or not, if it is an integer, i want it to move to the nested if and validate that it is a positive number, and show the error message in the label if it is not. If it is not a number at all i want it to show another message in the label. The problem that I am getting is that even if i put in a letter for the input it does not catch it and it continues on to the select case, which comes out 0.
I have a LINQ2Entity problem, I want to get the value, string, from a database, so I select FProducts.Serial_number, and to end the query, I do .ToDictionary. The problem is, it tells me that it doesn't have sufficient parameters, to convert ToDictionary. So I need something like select FProducts.Serial_number, Nothing). ToDictionary. Also FProducts.Serial_number, 0).ToDictionary doesn't work.
Sub GetStatistics(ByVal ProductNumbers As List(Of String), ByRef Passed As Integer, ByRef FailedProducts As List(Of String)) Passed = 0 FailedProducts = Nothing
I want to use explicit conversion (CType function in VB.NET) to convert the variable d from double type to integer type and store the result as 132.
Imports System.Console Module Module1
Sub Main()
[CODE]...
This is my code. But Visual Basic tells me an error: Error1Type 'i' is not defined.C:\Users\mihaispr\Desktop\Conversie explicita\Conversie explicita\Module1.vb1922Conversie explicita
I am trying to check this app. and make sure only numbers are placed into the textbox, but my tryparse isn't working.
Private Sub btnConvertC_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnConvertC.Click Dim intTemp As Integer 'holds the text input If Integer.TryParse(txtTemp.Text, intTemp) Then
I have an array of 5 objects and also 5 textboxes. I am wanting to check to see if the values in the corresponding textbox are valid for the type of object.I have currently hard coded this, I parse out the object type and then use a tryparse statement depending on the object type.
Can I do this automatically? Can I detect the type and use a tryparse statement for that type. Maybe something like:if objectarray(x).tryparse(textbox(x).text, nothing)
I have become accustomed to using TryParse for attempting to parse unknown types:
Dim b As Boolean Dim qVal As Boolean = If(Boolean.TryParse(Request.QueryString("q").Trim(), b), b, False)
or
bool b; bool qVal = (Boolean.TryParse(Request.QueryString("q").Trim(), out b) ? b : false;
So, just curious if someone knows a better way of doing this other than using a ternary operator.
public static class PrimitiveType { /// This function will return a parsed value of the generic type specified. /// </summary>
[code]....
Just pass in the type you're expecting as the generic and provide a string value to be parsed and a default value in case the string is not parsable. If you provide a class instead of a primitive type it will throw new ArgumentException("Generic type must be a valid Value Type that has a Parse method.");
The adultcombobox & childcombobox have value from 1 to 10, and none.I try put it in Do Loop like the code below, but the total price not come up so well, so I think I am having problem with the Do Loop and the Payment method.One more thing, do I need to Tryparse the combobox and use the selectedIndex ?
I am in my programming class and we had a small program to make that would check to see if an value that was entered is a integer and convert it to a Roman numeral. I know how to properly do it by putting the TryParse into the If...Then statement. What I am trying to do is to not use an If...Then statement and go just by a Case Selection statement. If it is not possible then that is cool with me, I am just trying to think outside the box. Here is what i have done with it: [code]....
When you do say "Case 1" it says it needs to be "Case CBool(1)." Using either "Case CBool(1)" or "Case 1 = 1" provides the same result .However the code shows no errors it doesn't do the conversion, it always displays the label's value as "I"
On all my assignments I am asked to make sure the data is valid - only numeric, no empty strings. And I keep wondering which is the best to use IsNumeric or TryParse. When I try both on coding they seem to do the same thing, and I don't seem to find my answer online. Any ideas of why to use one over the other.
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.
I am currently having a headache on how to solve this problem that i am facing. here is the situation: I have a combobox and a list box on the main form. The combobox will get the data from the ms access database. In the database, i have the details of a person's IC, Name and DOB say for eg on one entry I have D215311523C,SHAWN,13/04/1987 So now, my combobox on form load will show the list of dates in the database to allow the user to search base on the date itself by clicking on the selected date. So when the user clicks on the particular date say 13/04/1987, people in the database whose birthday is 13/04/1987 will be shown on the listbox.Meaning to say if i have 3 entries whose dates are the same 13/04/1987, 3 entries will appear. If there is only two entry, then two results will be shown. But now, when i do a single click on the date, one result will be shown. That is correct. But the problem is when i click on the same date again, three of the same results will be shown on the list box. that is it will display : 13/04/1987 13/04/1987 13/04/1987 which is not the case. Then it will show more duplicates of the same results if i click more times on the same date which should not be the case.
Dim n As Integer Dim numbers() As Integer Dim StartFrom As Integer Dim EndAt As Integer
I am using a datagrid in my where i am having four columns. In first column the parameter values are entered and in the second column measured value is entered and in third column the nominal value is entered.Inthe fourth column the result is displayed by subtracting the measured value and nominal values. I am doing this calculation in Datagrid cell validated event. What i want is,there will be many rows in the grid,when typing the value in the third column the corresponding result will be displayedin the rowof theresult column,save button will be displayed while the form loads,when the calculate part is completed that is there should not any cell of the resut column empty then i should enable the save butto.
I am encountering the following issue So i have a device that sends stuff at the serial port, i then parse it and put it into an array of bytes like that:
Dim HCI_Command_Rcvd_Byte() As Byte All good till here What i wanna do is make an array and put this result every time the serial port gives me a new result, for example:
[Code]...
Basically what i wanna do is let the port parse the messages, fill in the array with the result at an empty spot in this array and then i will have a separate thread that will look in into this array in each non empty space and after it looks into the non empty space it will use or discard the info and also mark this space as empty (after it checked)
Is there any way to use the TryParse method to check for letter text input?For example, a user needs to input a name in a text box. Is there anyway to check that input are all letters?
I just read about DataSet in VB.NET, it uses disconnected concept. My question is: if my apps has "List All" button that query data from 1 table in the database, and that table has "very very very" many rows, so my DataSet will be filled with those data and eat up memory. Can I limit the data that being put to the DataSet from that query? But I want to be able to retrieve the next data from the same query if the user want to see it?
For example: I have 1000 rows in my database, and i query all of them. But I just want 200 rows being inserted to my DataSet, but if the user want to see rows number 201 and so on, I want to be able to retrieve the next 200 rows, and so on. So it just like cutting those data into a group of 200 rows. Can I do this with the concept of "disconnected" of the DataSet?
How would I code a TryParse to get the input from customer from a textbox named Strands and convert it to a number (this number will always be a whole complete number, cannot be 5.6 or 4 1/2 or whatever) then have that Strand number be muliplied by the selected item in my listbox1. This listbox has an access database bound to it with 2 columns Size and Area, the Size equals the Area and I set the Value to the Area column but set the Size to show up in the list box. and the Strands textbox has to muliply by the Size picked, but by the Area # not the Size #. And the results of that multiplication showing up in another textbox named total.
ive got some simple problem i cant understand how to solve.
str(1) is an array and integer(or double, tried both) a(1) is an array and integer (or double, tried both) a(1) = a(1) + 1 Label1.Text = str(1) + a
the big part is where i get: operator '+' is not defined for types 'integer' and '1-dimensional array of integer'.why do i get that message and what does it mean? how do i make the code do what i want?
I'm trying to create a linked list of an array of integers. Why is the following implicit conversion required?
When I run the code that contains that conversion, I get the following error.
As a real-time data acquisition user control data (a packet of an array of bytes) arrives every second, is converted into an integer array and inserted into a linked list.
The most recently arrived data is painted as coordinates on a grid at the right of a PictureBox using Graphics.DrawLine (pen,X1,Y1,X2,Y2).
The oldest data (arriving 120 seconds ago) will be drawn at the leftmost portion of the Picturebox.
Why a linked list rather than a list? To display 120 views of time sequence data, the draw routine the most recently inserted node to a node that points to Nothing. How do I limit the length of the linked list to 120 nodes and always ensure that the last node points to Nothing?
Do While Not item Is Nothing item = item.NextItem Loop
I am a newbie in VB and I got a piece of code which can display the current running program. I need to use that in VB2005 and I got the below error message. Can anyone help how to fix it?[code]
I'm trying to convert a VB6 project to .NET, but I get problems with some callback functions, and the following message comes up: "AddressOf' expression cannot be converted to 'integer' because integer is not a delegate type" I've seen several solutions to similar problems like this, but I am not able to understand this issue with delegates.
After the conversion, the code look like this:
Declare Function vsmsgwSetDataPackageCB Lib "vsmsgwW.dll" (ByVal PACKAGE As Integer, ByRef arg As Integer) As Integer Dim arginitP As Integer
[Code]...
Which gives the error: Method 'Public Function PackageCB(HisNodeID As Integer, ByRef data() As Byte, ByVal length As Integer, ByRef arg As Integer) As Integer' does not have the same signature as delegate 'Delegate Function DelegatePackageCallback(hwnd As Integer, lparam As Integer) As Integer
this is for a BINGO game final project that I already turned in but this just bugged me that I could not get the sorting figured out. I am trying to get this to sort the random numbers in to columns under the correct letters but I keep getting the error Operator '>=' is not defined for types '1-dimensional array of Integer' and 'Integer' under the line:
I am new to EF Linq and I have been struggling with this query for a few days. From reading this forum, I have managed to get this far:
Dim noPic = (From f In myEntities.FriendLists Where (f.UserID = Profile.ID) Select f.FriendID).Except(From g In myEntities.GuestLists Where g.EventID = _id Select g.FriendID)
[Code]...
I am trying to get everybody from the FriendList who is not already on the GuestList to display in a Repeater control. After reading the forum I was able to append .First() to noPic at the myNoPic declaration and finally get a result but that only gave me the first element. Does anybody have any advice on how to accomplish this?
Why doesn't CDate(integer) work where integer has format of YYYYMMDD ?and why won't this stupid site let me submit such a short question when I have nothing else to add except some waffle at the end
