How-to Guide: Numbers and Operators in 2D Math Panic

Categorized | Math Panic, Tutorials

How-to Guide: Numbers and Operators in 2D Math Panic

Posted on 26 November 2011 by scAdmin

In response to a fan post on the Facebook page, here is a code snippet of how to generate random numbers and equations in 2D Math Panic.

Things to note:

Refer to the book Learning XNA 4.0 before following this example
The code below is from the “SpriteManager” class, a DrawableGameComponent
Initialize a static Random() object once, then use it when needed
In the Update() method, generate the operands and operators for the equation
Finally, calculate the correct answer!

The sample code below is a stripped-down version, to illustrate the points above. You will need a Draw() method to draw the equations on the screen, within an existing XNA project as shown in the referenced book.

using System;

public class SpriteManager : DrawableGameComponent
{
    // the 2 numbers used in each equation
    int num1 = 1;
    int num2 = 1;
    // string version of the operator, to show on the screen
    string mathOp = "+";
    // the correct answer, which will be re-calculated every time
    int correctAnswer = 2;
    // the static "random maker"
    static Random randomMaker;

    // set of Math operators
    public enum MathOpSet
    {
        Addition,
        SubtractionEasy,
        SubtractionHard,
        Multiplication,
        Division
    }
    // current choice of Math operator, initialized to addition
    public MathOpSet CurrentMathOp = MathOpSet.Addition;

    // constants
    int minNumber = 1;
    int maxNumber = 9;
    int minAnswer = 2;
    int maxAnswer = 20;

    public override void Initialize()
    {
        // initialize static random maker just once
        randomMaker = new Random();
    }

    public override void Update(GameTime gameTime)
    {
        // generate random numbers to use in equation
        var randomNum1 = randomMaker.Next(minNumber, maxNumber);
        var randomNum2 = randomMaker.Next(minNumber, maxNumber);

        // choose an operator from the set of operators
        int opChoice = randomMaker.Next(1, 6); // 1 through 5
        switch (opChoice)
        {
            case (1):
                {
                    CurrentMathOp = MathOpSet.Addition;
                    mathOp = "+";
                    num1 = randomNum1;
                    num2 = randomNum2;
                    correctAnswer = num1 + num2;
                }
                break;
            case (2):
                {
                    CurrentMathOp = MathOpSet.SubtractionEasy;
                    mathOp = "-";
                    num1 = Math.Max(randomNum1, randomNum2);
                    num2 = Math.Min(randomNum1, randomNum2);
                    correctAnswer = num1 - num2;
                }
                break;
            case (3):
                {
                    CurrentMathOp = MathOpSet.SubtractionHard;
                    mathOp = "-";
                    num1 = Math.Min(randomNum1, randomNum2);
                    num2 = Math.Max(randomNum1, randomNum2);
                    correctAnswer = num1 - num2;
                }
                break;
            case (4):
                {
                    CurrentMathOp = MathOpSet.Multiplication;
                    mathOp = "x";
                    num1 = randomNum1;
                    num2 = randomNum2;
                    correctAnswer = num1 * num2;
                }
                break;
            case (5):
                {
                    CurrentMathOp = MathOpSet.Division;
                    mathOp = "/";
                    num1 = randomNum1 * randomNum2;
                    num2 = randomNum2;
                    correctAnswer = randomNum1;
                }
                break;
            default:
                {
                    CurrentMathOp = MathOpSet.SubtractionEasy;
                    mathOp = "-";
                    num1 = Math.Max(randomNum1, randomNum2);
                    num2 = Math.Min(randomNum1, randomNum2);
                    correctAnswer = num1 - num2;
                }
                break;
        }
    }
}

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