Beginner Question

This is a discussion on Beginner Question within the C++ Programming forums, part of the General Programming Boards category; How do I fix this? I don't know how to convert inputted choice to equal the If statement. Code: #include ...

  1. #1
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    Beginner Question

    How do I fix this? I don't know how to convert inputted choice to equal the If statement.

    Code:
    #include "stdafx.h"
    
    #using <mscorlib.dll>
    
    using namespace System;
    
    int _tmain()
    {
    	double cont = 1, r, theta, x, y, A, B;
        __wchar_t choice;
    	while (cont == 1)
    	{
       	Console::Write( S"A	Convert Polar Coordinates to Cartesian \n");
    	Console::Write( S"B	Convert Cartesian Coordinates to Polar \n");
    	Console::Write( S"C	Determine Roots of a quadratic equation \n");
    	choice = Char::Parse(Console::ReadLine());
    
       if ( choice == A)
       {
        Console::Write( S"R: ");
        r = Int32::Parse( Console::ReadLine());
    	Console::WriteLine( S"Theta: ");
    	theta = Int32::Parse( Console::ReadLine() );
    	x = r * Math::Cos(theta);
    	y = r * Math::Sin(theta);
    	Console::Write( S"X: {0}", x.ToString());
    	Console::Write( S"Y: {0}", y.ToString());
    	return 0;
       }
       if ( choice == B)
       {
        Console::WriteLine( S"X: ");
    	x = Int32::Parse( Console::ReadLine() );
    	Console::WriteLine( S"Y: ");
    	y = Int32::Parse( Console::ReadLine() );
    	r = Math::Sqrt(Math::Pow(x, 2)+Math::Pow(y, 2));
    	theta = Math::Atan(y/x);
    return 0;
       }
    	}
    }

  2. #2
    MFC killed my cat! manutd's Avatar
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    Methinks this is C#. This is a C++ forum. Mods, please move.
    Silence is better than unmeaning words.
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  3. #3
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    This is C++ with .net

  4. #4
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    Code:
       if ( choice == __wchar_t('A'))
    .
    .
       elseif ( choice == __wchar_t('B'))

  5. #5
    MFC killed my cat! manutd's Avatar
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    Oh, OK. My fault, I haven't used .NET in so long.
    Silence is better than unmeaning words.
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  6. #6
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    Quote Originally Posted by swoopy
    Code:
       if ( choice == __wchar_t('A'))
    .
    .
       elseif ( choice == __wchar_t('B'))
    Thanks for the help but, inputting A still doesn't bring up thing.

  7. #7
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    Nevermind it works. Thanks!

  8. #8
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    What does it mean when it says unreferenced local variable, (A and B)?

  9. #9
    Kiss the monkey. CodeMonkey's Avatar
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    It means you didn't "use" A or B.
    Code:
      double cont = 1, r, theta, x, y, A, B;
        __wchar_t choice;
            while (cont == 1)
            {
            Console::Write( S"A     Convert Polar Coordinates to Cartesian \n");
            Console::Write( S"B     Convert Cartesian Coordinates to Polar \n");
            Console::Write( S"C     Determine Roots of a quadratic equation \n");
            choice = Char::Parse(Console::ReadLine());
    
       if ( choice == A)
    Maybe the compiler is warning you of this undefined behavior. Technically, the variable is referenced by the == operator, no? I don't know. Initialize your variables.
    Last edited by CodeMonkey; 01-23-2007 at 07:44 PM. Reason: preposition error
    "If you tell the truth, you don't have to remember anything"
    -Mark Twain

  10. #10
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    Hi, thanks for all the answers.. one more question

    Code:
       if ( choice == __wchar_t('A'))
       {
        Console::Write( S"R: ");
    	r = Double::Parse( Console::ReadLine());
    	Console::Write( S"Degrees: ");
    	degree = Double::Parse( Console::ReadLine() );
    	rad = degree  * (Math::PI/180);
    	Console::WriteLine("");
    	x = r * Math::Cos(rad);
    	y = r * Math::Sin(rad);
    	Console::WriteLine( S"X: {0}", x.ToString());
    	Console::WriteLine( S"Y: {0}", y.ToString());
       }
    Do you guys see anything wrong with this?
    It seems to work fine until X or Y is suppose to equal 0.. it gives some e-16 value.

  11. #11
    Kiss the monkey. CodeMonkey's Avatar
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    Hm. Your trig funtions are either returning terribly small numbers, or you're having floating point issues. To debug, every time a double is assigned, print out its value right afterwards to make sure things are what you expect them to be.
    "If you tell the truth, you don't have to remember anything"
    -Mark Twain

  12. #12
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    Everything is fine until:

    Code:
    	
    x = r * Math::Cos(rad);
    y = r * Math::Sin(rad);
    Where it works except when rad is say PI..

  13. #13
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    How do you cut off a Double variable after say 2 digits?

  14. #14
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    >How do you cut off a Double variable after say 2 digits?
    In standard C++, you can do this:
    Code:
    #include <iostream>
    #include <iomanip>
    
    int main()
    {
       double num = 5.12345;
    
       std::cout << std::setprecision(2) << std::fixed << num << '\n';
    }
    I have no idea how to do it in .NET.

    Also just so you know:
    Code:
       if ( choice == __wchar_t('A'))
    I'm not positive, but I believe you can write this as:
    Code:
       if ( choice == T('A'))

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