how to calculate any kind of formula? RSS

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  bonsai8008

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  how to calculate any kind of formula?

  Aug 12, 2019 05:49 AM|bonsai8008|LINK

  Hi

  I have the following problem: I have any formula: e.g. (10+5)^3-255/5...

  In asp classic I could calculate the formula by using: execute("result = " & Formula)

  In asp.net I can't use 'execute' anymore. how can I calculate the formula? I had a look in the math-class but can't find there anything.

  best regards

  Chris

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  Yang Shen

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  Re: how to calculate any kind of formula?

  Aug 12, 2019 07:06 AM|Yang Shen|LINK

  Hi bonsai8008,

  bonsai8008

  In asp.net I can't use 'execute' anymore. how can I calculate the formula? I had a look in the math-class but can't find there anything.

  As far as i know, in asp.net there's no such method to calculate a formula in a string format.

  You may need to write your own calculate method. I believe you can find what you want here: MathParser.

  Best Regard,

  Yang Shen

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  bonsai8008

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  Re: how to calculate any kind of formula?

  Aug 12, 2019 01:52 PM|bonsai8008|LINK

  Hi Yang Shen

  Thanks for your the link.

  What a pity. Something quite interesting and surly often used is in asp.net not usable anymore.

  Will try to find out how to do it.

  best regards

  Chris

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  mgebhard

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  Re: how to calculate any kind of formula?

  Aug 12, 2019 03:04 PM|mgebhard|LINK

  IIRC, Server.Execute() invokes an asp page.  Eval() can invoke a string equation.

  In ASP.NET is a different framework which uses objects but you can use code blocks to do something similar.

  Results = <%= 1+2+3 %>

  Or from the Code behind.

  Results = <%= Results %>

          public decimal Results { get; set; }
          protected void Page_Load(object sender, EventArgs e)
          {
              Results = 1 + 2 + 3;
          }

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  bonsai8008

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  Re: how to calculate any kind of formula?

  Aug 15, 2019 09:46 AM|bonsai8008|LINK

  Thanks to all for the answers

  I found out an easy way:

  1. you have to activate in the project the reference "Microsoft Script Control 1.0". this has the effect that in the directory "/bin" you will get the file "Interop.MSScriptControl.dll"
  2. then you can use the following function:
     
     Formel = (5+3)*(8/2)+3*5
     Resultat = BerechneFormel(Formel)
     
     

     Public Function BerechneFormel(Formula As String) As Double
         Dim SC As New MSScriptControl.ScriptControl
         Dim Result As Double

         Response.Write("<br>Z 1050) Formula: " + Formula)
         SC.Language = "VBSCRIPT"

         Formula = Replace(Formula, ".", "") 'mögliche Tausendertrennung
         Formula = Replace(Formula, ",", ".") 'Umwandlung in amerikanische Zahlen
     
         Try
            'SHOW THAT IT WAS VALID
            Result = Convert.ToDouble(SC.Eval(Formula))
            'MessageBox.Show("Math success, " & Formula & " equals " & Result.ToString)
        
         Catch ex As Exception
            'SHOW THAT IT WAS INVALID
            'MessageBox.Show("Not a valid math formula for a double.") '==> you need a box called "MessageBox"
         End Try
     
         BerechneFormel = Result
         'Response.Write("<br>Z 1063) Result: " + Result.ToString)
     End Function