[Visual Basic 10] - Problems converting String to Double

[Nova Prospekt]

I currently am making a small little program that takes a string with variables (For Right Now, just "X"), and exports the data an external graph [i](not important information)[/i]

As I was told, Strings with Numbers or Equations(IE 9 + 3) could be solved and converted to Integers/Doubles easily, Yet it seems to be having trouble here

        Dim Arguments(200) as double

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        'Send information
        Dim STR, Temp As String
        Dim Degree, X As Double
        'Get the RAW string
        STR = TextBox1.Text.ToUpper

        'Make sure the string is legitimate
        For X = 0 To STR.Length - 1
            Temp = STR.Substring(X, 1)

            If IsNumeric(Temp) Or Temp = "X" Or Temp = "." Or Temp = " " Or Temp = "+" Or Temp = "-" Or Temp = "/" Or Temp = "*" Or Temp = "^" Then
                'Clear
            ElseIf Temp = "Y" Or Temp = "Z" Or Temp = "A" Or Temp = "B" Or Temp = "C" Or Temp = "D" Then
                'Change to X 
                STR.Insert(X, "X")
            Else
                MsgBox("The entered equation could not handle '" & STR.Substring(X, 1) & "'. Fix this Character and Retry")

                Exit Sub
            End If
        Next
        Temp = 0

        'Find out what it do.
        'Degree = STR.IndexOf((vbInteger.ToString & "X"), 0)
        FofX = STR

        'Accept X as arguments
       For X = 0 To 200
            STR = STR.Replace("X", " * " & X)
            STR = STR.Trim()
            STR = ("1 " & STR)
            'The Strinng should now be solvable

            Arguments(X) = Double.Parse(STR)
           'Wont convert?
        Next

    End Sub

The error I get is similar to this [b]"Conversion from string "(0)^2 + 49(0) + 7" to type 'Double' is not valid."[/b] (When X^2 + 49x + 7 was entered)

Im not sure what Im doing wrong... Any Ideas?

[editline]25th January 2011[/editline]

Hell Ill even listen to a theory, shits ridiculous...

[editline]26th January 2011[/editline]

*Whistles* 11 people of presumably basic skills in VB cant even get this one.

Im boned. :suicide:

[editline]26th January 2011[/editline]

It seems that VB throws a fit when It tries to get the sum of a string that is literal
IE ("6 + 7") rather than (6 + 7).

However it assues 49(0) is an array without the quotation marks.... An easy fix..

Problem solved right, hahaha
Not at all.

I need to find a way to get the literal string im reciving from a text box, to a straight up equation still...

[Venice Queen]

you need to parse it, rearrange the tokens into postfix, and evaluate it

[Liquid Helium]

Integer.Parse turns a sting "763" into a number 763, that should be what you need

[Goz3rr]

I always just used Convert.ToDouble

[ShaRose]

Whoever told OP that Double.Parse (or Double.TryParse) would parse expressions was lying to him / an idiot. Seems he could not figure this out himself.

Next time I suggest you look at documentation. Seening as Visual Basic 10 would be part of .net, your first search should have been on MSDN. Which find this.

[url]http://msdn.microsoft.com/en-us/library/fd84bdyt.aspx[/url]

I also suggest you look into C# as well.

Oh, and Goz3rr, Convert.ToDouble calls Double.Parse. It checks for null, which is the first real check done anyways.

[Nova Prospekt]

Well shit sailor, Maybe im missing something;
It kind of looks like you sent me a link, telling me to [i]use[/i] Double.Parse for this.

Contradicting isn't it?

[editline]26th January 2011[/editline]

- Updated Code Snip, Minor changes in changing STR's formating

[ShaRose]

[QUOTE=Nova Prospekt;27674756]Well shit sailor, Maybe im missing something;
It kind of looks like you sent me a link, telling me to [i]use[/i] Double.Parse for this.

Contradicting isn't it?

[editline]26th January 2011[/editline]

- Updated Code Snip, Minor changes in changing STR's formating[/QUOTE]

What I am trying to say is that Double.Parse does not solve equations. You will need to either code an equation solver yourself, or find one.

[Nova Prospekt]

God damn ass raped :(

[Pepin]

Be sure that you use some documentation so you are aware what the function does and what parameters it takes. In this case, it takes one string and outputs one number.

[Loli]

[QUOTE=Nova Prospekt;27663780]
(When X^2 + 49x + 7 was entered)
[/QUOTE]

Quadratic Equation Solver I see. We've all been there :downs:
I don't know the answer, but I think I have one in C# lying around if you want it...

[Goz3rr]

[QUOTE=ShaRose;27667321]
Oh, and Goz3rr, Convert.ToDouble calls Double.Parse. It checks for null, which is the first real check done anyways.[/QUOTE]

What does it matter if it works? I don't see the problem here.

[ShaRose]

[QUOTE=Goz3rr;27706492]What does it matter if it works? I don't see the problem here.[/QUOTE]

A very minute addition to call time.

I mentioned it because it seemed that you thought it did something extra.

[Nova Prospekt]

[QUOTE=Loli;27697351]Quadratic Equation Solver I see. We've all been there :downs:
I don't know the answer, but I think I have one in C# lying around if you want it...[/QUOTE]

Well considering the possibility of VB running codes of other languages, That would be appreciated.

[Pepin]

I found this. It's for C++.

[URL]http://warp.povusers.org/FunctionParser/[/URL]

For C#
[URL]http://www.bestcode.com/html/bcparser_net.html[/URL]

This one seems interesting.

[url]http://www.codeproject.com/KB/recipes/FastMathParser.aspx[/url]

[ShaRose]

[QUOTE=Pepin;27788809]I found this. It's for C++.

[URL]http://warp.povusers.org/FunctionParser/[/URL]

For C#
[URL]http://www.bestcode.com/html/bcparser_net.html[/URL]

This one seems interesting.

[url]http://www.codeproject.com/KB/recipes/FastMathParser.aspx[/url][/QUOTE]

If it's .net, it will work for the OP. It even comes with a VB sample.