Fast Math Expression Evaluator (eval Function)
Mar 16, 2004
I need to execute scripted text formulas. I believe that in VB 6 and/or VBA there was a method EVAL() that did the job, eg: [Code] As it seems, such a method does not exist in VB.NET. [url] The method works fine but due to its comprehensive layout its not that fast (as i need to call it myriad of times) Does anyone have a SIMPLE, FAST, straight forward math expression method? Or anyone knows how to use the old EVAL method in VB.NET?
View 10 Replies
ADVERTISEMENT
May 21, 2010
I need to test a logical expression held in a string to see if it evaluate to TRUE or FALSE.(the strig is built dynamically)For example the resulting string may contain "'dog'<'cat' OR (1>4 AND 4<6)". There are no variables in the string, it will logically evaluate. It will only contain simple operators = > < >< >= <= and AND , OR and Open and Close Brackets, string constants and numbers. (converted to correct syntax && || etc.)
I currently acheive this by creating a jscipt function and compiling it into a .dll. I then reference the .dll in my VB.NET project.
class ExpressionEvaluator
{
function Evaluate(Expression : String)
{
return eval(Expression);
}
}
Is there a simpler method using built in .NET functions or Lamdba expressions.
View 2 Replies
Sep 20, 2009
Is there any way to parse a string in vb.net (like, built in methods), that can do math like Eval can? For example, 3+(7/3.5) as a string would return 2.
I am not asking for you to code this for me, I just want to know if there is a built in way to do this, if there is not I will code it myself.
I can wager that it would not be able to parse stuff like Sin(90) on its own, and I understand that would need to be replaced by Math.Sin(90).
View 5 Replies
Jan 31, 2011
I want to execute the code that is passed as a string to my function, the code will be passed at runtime. This is an example code that may be passed as a string to my function. p is a dataset, which is declared and has some values, this code is executed in a asp.net page
p.Tables(0).Rows(0)("disp_status") = "Approved by CEO";
p.Tables(0).Rows(0)("status") = "Approved";
Session("fnc") = "generate po";
[Code]...
View 1 Replies
Jul 31, 2010
can i save the returning value of eval function in a variable and use it wherever i want? i can call it just in <asp: .... tags. i can't use them in vb methods. is it possible?
View 1 Replies
Oct 12, 2010
I am trying to write following expression on a datacolumn. But it results in error:Replicate('*', nLevel) + NameWhere: Replicate() is a user defined function (in a module). nLevel and Name are two other columns in same data table.
View 3 Replies
Jan 9, 2007
does VB.NET include the Mathematical Integration/Derivation functions in the Library? If so where are
they, I couldn't find them? If not, any third-party libraries you would recommend?
View 3 Replies
May 9, 2010
I am making a calculator that accepts large number (represented as strings) and performs basic math functions on them. So far I have Add and Multiply figured out.
Here is addition
Private Function Add(ByVal Number1 As String, ByVal Number2 As String) As String
Dim num1, num2, r, total As New Integer
Dim sum As String = ""
[Code].....
I saw something like this in the code bank but the examples there were from VB6(?) and were hugely inefficient (compared his Add and Multiply examples to mine, his having way more code and loops.)
View 6 Replies
Apr 3, 2008
I was wondering if someone could explain the logic behind the MidpointRounding enumeration for the Math.Round function. The two enumerations are AwayFromZero and ToEven where, based on the given precision, the former will return the nearest value away from zero toward positive or negative infinity (based on the value's sign) and and letter will provide the nearest even number.
[Code]...
View 1 Replies
Nov 29, 2010
how to go about populating some text boxes with results from calculations. To be more specific, I'm trying to do some trig to calculate various parts of a ci0rcle and will be populating any two of the text boxes then click on a button to get the missing values. I was thinking along the lines of a loop until all values have been calculated.
View 14 Replies
Mar 5, 2012
well i am having a couple of issues with this particular homework problem and this is my first programming class so there is probably quite a few mistakes well the homework problem is to take three double values entered by a user and display the largest and smallest using math.max and math.min and display the smallest and largest so i thought i could use a listbox and take the values that went to the listbox and assign variables to each so i can try to use each variable in the math.max and min but im not making it to far and i actually might be way off
[Code]...
View 4 Replies
Jun 10, 2011
I just want to ask if it is possible to create a function that accepts an expression into its arguments. Just like what IIF do. Ex: Dim strResponse as String = IIF(Msgbox("Select Yes or No", vbYesNo) = vbYes, "Yes", "No") I forgot the code, but its the thought that counts.
View 1 Replies
May 9, 2010
1.print the cars which are fast moving cars.
i have written this code but it shows message Cannot have aggregate function in expression[code]...
View 7 Replies
Apr 24, 2012
Should I be concerned about the performance of the Compile method here?[code]...
The reason I want the lambda expression is because I want that function to be able to get all the way through LINQ-to-SQL to be converted to SQL. The reason I want the direct version is because I have other code that I want to validate individual serial numbers before submitting changes. And I fear that GetValidSerialNumbers.Contains(serialNumber) will execute a more-complex-than-necesssary query.
View 1 Replies
Jan 13, 2010
i want to set a complex column expression truncate(cdbl(Today()-date2)/30)*(parent(parentchild).field1/parent(parentchild(filed2)))but truncate function is not available !
View 12 Replies
Jan 23, 2009
i read an article about datacolumn.expression property here [URL]. this is really great. but i was just wondering, for my case i want to use my custom function to use in the expression. basically, on my datatable i added an unbound column AGE. when i display records, i just want the age textbox to be populated with the computation of the person's age based on birthdate.
View 7 Replies
Aug 13, 2010
Having problem understanding Delegate error. Error says expression expected, How do I fix?Here is the offending line (#259)....
mylist.ForEach(Delegate Function(P As linkItem) As System.Char[] )
Here is the entire code.
<script language="VB" runat="server">
Function sectionTitle(ByRef f As String)
'Open a file for reading
[code]....
View 3 Replies
Dec 24, 2011
This is my .aspx page code: -
<asp:Button ID="btnProcess" runat="server" Text="Place" OnClick="btnProcess_Click"
CommandArgument='<%# Eval("intId") & "~" & Eval("IdECompleted") & "~" & Eval("dtECompletion") & "~" & Eval("strName") & " " & Eval("strCode") & " " & [code]....
I want to use it like below but gets error: -
Private Sub Grd_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles Grd.RowDataBound
If Session("poweradmin") = True Then[code].....
View 1 Replies
Dec 8, 2011
I only want to show the credit card info section if the Eval expression evaluates to true, but it gives me and error saying I can only use it in the context of a databinding control, I know I have to put the #, but vb then says that I must use If() or IIF(). What is the correct syntax.
[Code]...
View 1 Replies
Jul 1, 2009
I am working on an application in Visual Basic Express using an Access 2000 database.I am trying to get athe following SQL query to work but get an error in Access.
The query is:
SELECT [ID], [Title], [Author], [Series], [YearPublished], [ISBN], [CoverPrice], [Style], [Condition], [Signed], [Comments], Count([Title]) AS CountOfBooks, Sum([CoverPrice]) AS TotalCoverPrice
FROM tblBooks
WHERE ID=[@ID];
The error is:"You have tried to execute a query that does not include the spec ified expression 'ID' as a part of the aggragate function."
The query works fine without the 'Count' and 'CoverPrice' count and sum to the query.
View 1 Replies
Jul 16, 2009
I'm trying to bind an image using Eval() with VB.NET and ASP.NET, but am running into issues:
Code snippet
<bri:ThumbViewer Id="Th1" runat="server"
ImageUrl='<%# Eval("Name", "~/SiteImages/ram/3/{0}") %>'
Height="100px"
[Code].....
View 5 Replies
May 30, 2011
Ok so if you look at the markup of this page: [URL]
You'll see that it uses eval and unescape to make it look like this in it's markup "%73%65%6c%66%2e%64%6f%63%75%6d%65%6e%74%2e%77%72%69%74%65%6c and so on...."
I'm trying to make a program using httpwebrequest that will grab this long string off the website using regex then decode this and put it in a textbox. I know how to accomplish the first two parts how I could decode this in VB.
View 6 Replies
Mar 1, 2010
I have a SQLDataSource that is bound to a ListView control but I want to place parts of the bound record into the HTML TITLE attribute. Here is my codebehind file that I want to change so it can use Eval to construct a dynamic TITLE based on the data content[code]...
View 1 Replies
Dec 30, 2010
I am working on my first project with the Entity Framework and am having some difficulty displaying advanced information with the EntityDataSource and a ListView.
For example, given the two entities:
Item
Name
[code].....
View 1 Replies
Feb 8, 2009
I've written a piece of software which extracts information from the web and stores it all to a local SQL Server database which all works well. However, I now want to add additional functionality where any user can go in and create a template which would be run when every synch has complete which would save as an HTML file. I've set up whole thing. Information is stored in a backend XML file which is processed when the synch completes. However, I want this information to check delimeters in the string and process it as code.
View 2 Replies
May 31, 2012
I have a repeater which takes 270 seconds to render and actually ends up crashing all browsers. The SQL to retrieve the data takes about 10 seconds. I wanted to remove the Eval's to see if that speeds up things a bit, but I am having trouble with the correct syntax. I have doubts that this would actually improve performance as I am dealing with 150,000 records. Would a GridView or other control be faster? Would using LINQ to SQL improve performance? Here is the code for the Eval:
[Code]...
View 1 Replies
Mar 22, 2012
I want to create an ExpressionTree where a Func(of Vector, Vector, Vector, Vector, Double, Double, Vektor) should be called. So I use
Expression.Call(Forces(0).Function.Method, {Vec1, Vec2, Vec3, Vec4, Double1, Double2})(Vec1-4, Double1-2 are declared as ParameterExpression and Forces(0).Function as Func(of Vector, Vector, Vector, Vector, Double, Double, Vector). But I get an AgrumentException, because Forces(0).Function.Method has seven Arguments. (System.Runtime.CompilerServices.Closure as seventh argument at Index 0).
View 2 Replies
Jan 30, 2012
I have following error in my code,how to remove it from code
Protected Sub addListItems()
Dim now As DateTime = DateTime.Now
Dim past As DateTime = now.AddDays(-20)
[code]....
The error is in last line on function "Expression Expected"
ConvertAll(Function(dt)
View 1 Replies
Apr 21, 2012
<%If (Eval("NewPrice")) =0 Then%>
<% Session("OrigenalPrice") = True%>
<asp:Label ID="Pricelabel" runat="server" Text='<%# Eval("Price") %>' />
<%Else%>
[code].....
View 1 Replies
Mar 22, 2012
I want to pass an optional parameter to a function of type System.Drawing.Color. The problem I am having is that when I declare the function it says "Constant expression is required" but I have tried variations of the following, including integers, full qualified indentifiers, even old vbWhite constants to no avail.
[Code]...
View 14 Replies
