probleam with method sin, cos & tan

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Hai, i have probleam with my code, currently i am create scientific calculator which have function sin, cos & tan. The code i create it not working because every time i convert the function it will show 0 as answer.Please advice me how to correct my code here.

VB

Public Class Form1
    Dim total1, total2 As Double
    Dim [Operator] As String
    Const conversionFactor As Double = Math.PI / 180
Dim result As Double
        total2 = Val(answer.Text)

        Select Case [Operator]
             Case "SIN"
                result = Math.Sin(total1 / conversionFactor)
                answer.Text = result
            Case "COS"
                result = Math.Cos(total1 / conversionFactor)
                answer.Text = result
            Case "Tan"
                result = Math.Tan(total1 / conversionFactor)
        End Select
        answer.Text = result
    End Sub

Posted 6-Sep-11 12:31pm

Iswandi Abdul Rahman

Updated 6-Sep-11 12:32pm

Wendelius

v2

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Wendelius · Accepted Answer · 2011-09-06T12:36:00

Solution 1

If this is all of the code, the first problem seems to be that you use total1 variable, but you don't assign a value to it. Also you don't set the operator so none of the cases are hit.

Put a breakpoint to the beginning of the code and go step-by-step to see intermediate results and behaviour.

Posted 6-Sep-11 12:36pm

Wendelius

Updated 6-Sep-11 12:39pm

v2

Comments

Espen Harlinn 6-Sep-11 19:17pm

Good reply - 5'ed

Wendelius 7-Sep-11 1:08am

Thanks Espen :)

Espen Harlinn · Accepted Answer · 2011-09-06T12:37:00

Solution 2

The usual way to handle this is to set a breakpoint at

VB

total2 = Val(answer.Text)

That will allow you to inspect what's going on as the method executes.

This might be interesting: Debugging in Visual Studio[^]

Best regards
Espen Harlinn

Posted 6-Sep-11 12:37pm

Espen Harlinn

Comments

Sergey Alexandrovich Kryukov 6-Sep-11 19:53pm

This is correct, of course, my 5.
However, I don't feel much enthusiastic about this project looking at OP's samples. I tried to give some advice to make things reasonable, maybe a bit too lapidary -- please take a look at my solution.
--SA

Espen Harlinn 7-Sep-11 4:47am

Thanks Sergey!

Sergey Alexandrovich Kryukov · Accepted Answer · 2011-09-06T13:14:00

Case with immediate constants "SIN", "COS" etc. is the worst you could invent. If these are buttons, give each variable a semantic name and add a handler to each button individually, but share the handler code, parametrize if. A parameter could be of some enumeration type, not string:

C#

enum Operator { sin, cos, tag, /*...*/}

Make a dictionary which finds a delegate instance by each operator's value:

C#

using OperatorDictionary = System.Collections.Generic.Dictionary<Operator, OperatorApplication>;

//...

delegate double OperatorApplication(double left, double right);

The same idea works if you parse text with expression. Parse it into some logical structure, where the operator code is enumeration shown above, not string. Something like that. With your immediate constants of the string type, even with explicit string constants, you will get sunk in support issues pretty soon. Don't lock yourself.

—SA