1
\$\begingroup\$

I'm trying to find a way to make this code more efficient than using a lot of if statements because there are a lot of combinations. The final result variable is an equation made from randomly chosen arithmetic signs and the operands are random numbers between 1 and 10 to create an equation. But after 2 operands there are a lot of combinations so I need help finding a different way so I don't have to manually put in all the possible combinations in if statements. The equations can either have two operators at the least to 4 operators and up to to 5 operands per equation so each equation will be randomly created.

public class MathEngine : MonoBehaviour## Heading ##
{
public Text equationText;
public bool setFixedNumOfOperands;

public bool sumOnly;
public bool subtractionOnly;
public bool multiplyOnly;
public bool divideOnly;

private List<string> randomSigns;
private List<int> operandList;


[Range(2,5)] 
public int numberOFOperands;

public int operandRange;

public int operandRangeMinimum = 1;
public int operandRangeMaximum= 10;

string randomsigns;


private float finalResult;

private float operand1;
private float operand2;
private float operand3;
private float operand4;
private float operand5;


// Use this for initialization
private void Start()
{
    operandRange = Random.Range(operandRangeMinimum, operandRangeMaximum + 1);

    operand1 = Random.Range(operandRangeMinimum, operandRangeMaximum + 1);
    operand2 = Random.Range(operandRangeMinimum, operandRangeMaximum + 1);
    operand3 = Random.Range(operandRangeMinimum, operandRangeMaximum + 1);
    operand4 = Random.Range(operandRangeMinimum, operandRangeMaximum + 1);
    operand5 = Random.Range(operandRangeMinimum, operandRangeMaximum + 1);

    operandList = new List<int>();
    randomSigns = new List<string>();

    randomSigns.Add("+");
    randomSigns.Add("-");
    randomSigns.Add("*");
    randomSigns.Add("/");

    string sign1 = randomSigns[Random.Range(0, 4)];
    string sign2 = randomSigns[Random.Range(0,4)];
    string sign3 = randomSigns[Random.Range(0, 4)];
    string sign4 = randomSigns[Random.Range(0, 4)];
    string sign5 = randomSigns[Random.Range(0, 4)];

    string sign =  randomSigns[Random.Range(0, 4)];

    if (setFixedNumOfOperands == false)
    {
        numberOFOperands = Random.Range(2, 6);


        for (int i = 0; i < numberOFOperands; i++)
        {
            //randomsigns = randomSigns[Random.Range(0, 4)];
            operandList.Add(i);
        }
        Debug.Log("random: " + numberOFOperands);
        Debug.Log("number of operands in list: " + operandList.Count);

     }
    else
    {
        for (int i = 0; i < numberOFOperands; i++)
        {
            operandList.Add(i);
        }
        Debug.Log("number of operands in list: " + operandList.Count);

    }


    //----------2 sign combinations 3 operands--------
    if (numberOFOperands == 3 && setFixedNumOfOperands)
    {
        //----If all signs are the same-----
        if (sign1 == "+" && sign2 == "+")
        {
            finalResult = operand1 + operand2 + operand3;
        }
        if (sign1 == "-" && sign2 == "-")
        {
            finalResult = operand1 - operand2 - operand3;
        }
        if (sign1 == "*" && sign2 == "*")
        {
            finalResult = operand1 * operand2 * operand3;
        }

        if (sign1 == "/" && sign2 == "/")
        {
            finalResult = operand1 / operand2 / operand3;
        }

        //---------Addition Combinations---------
        if (sign1 == "+" && sign2 == "/")
        {
            finalResult = (operand1 + operand2) / operand3;
        }
        if (sign1 == "+" && sign2 == "-")
        {
            finalResult = operand1 + operand2 - operand3;
        }
        if (sign1 == "+" && sign2 == "*")
        {
            finalResult = operand1 + (operand2 * operand3);
        }

        //---------Subtraction Combinations---------
        if (sign1 == "-" && sign2 == "/")
        {
            finalResult = (operand1 - operand2) / operand3;
        }
        if (sign1 == "-" && sign2 == "+")
        {
            finalResult = operand1 - operand2 + operand3;
        }
        if (sign1 == "-" && sign2 == "*")
        {
            finalResult = operand1 - (operand2 * operand3);
        }
        //---------Multiplication Combinations---------
        if (sign1 == "*" && sign2 == "/")
        {
            finalResult = (operand1 * operand2) / operand3;
        }
        if (sign1 == "*" && sign2 == "+")
        {
            finalResult = (operand1 * operand2) + operand3;
        }
        if (sign1 == "*" && sign2 == "-")
        {
            finalResult = (operand1 * operand2) - operand3;
        }
        //---------Division Combinations---------
        if (sign1 == "/" && sign2 == "*")
        {
            finalResult = (operand1 / operand2) * operand3;
        }
        if (sign1 == "/" && sign2 == "+")
        {
            finalResult = (operand1 / operand2) + operand3;
        }
        if (sign1 == "/" && sign2 == "-")
        {
            finalResult = (operand1 / operand2) - operand3;
        }

        //--------if only 2 signs and 3 operands -------------
        equationText.text = operand1 + " " + sign1 + " " + operand2 + " " + sign2 + " " + operand3 + " " + "= " + finalResult;
    }


    //----------3 sign combinations 4 operands--------
    if (numberOFOperands == 4 && setFixedNumOfOperands)
    {
        //----If all signs are the same-----
        if (sign1 == "+" && sign2 == "+" && sign3 == "+")
        {
            finalResult = operand1 + operand2 + operand3 + operand4;
        }
        if (sign1 == "-" && sign2 == "-" && sign3 == "-")
        {
            finalResult = operand1 - operand2 - operand3 - operand4;
        }
        if (sign1 == "*" && sign2 == "*" && sign3 == "*")
        {
            finalResult = operand1 * operand2 * operand3 * operand4;
        }

        if (sign1 == "/" && sign2 == "/" && sign3 == "/")
        {
            finalResult = operand1 / operand2 / operand3 / operand4;
        }

        //---------Addition Combinations---------
        if (sign1 == "+" && sign2 == "/" && sign3 == "/")
        {
            finalResult = (operand1 + operand2) / operand3 / operand4;
        }
        if (sign1 == "+" && sign2 == "-" && sign3 == "-")
        {
            finalResult = operand1 + operand2 - operand3 - operand4;
        }
        if (sign1 == "+" && sign2 == "*" && sign3 == "*" )
        {
            finalResult = operand1 + (operand2 * operand3) * operand4;
        }
        //---------
        if (sign1 == "+" && sign2 == "+" && sign3 == "*")
        {
            finalResult = operand1 + operand2 + (operand3 * operand4);
        }
        if (sign1 == "+" && sign2 == "+" && sign3 == "/")
        {
            finalResult = operand1 + operand2 + (operand3 / operand4);
        }
        if (sign1 == "+" && sign2 == "+" && sign3 == "-")
        {
            finalResult = operand1 + operand2 + operand3 - operand4;
        }
        //-----------

        if (sign1 == "+" && sign2 == "*" && sign3 == "+")
        {
            finalResult = operand1 + (operand2 * operand3) + operand4;
        }
        if (sign1 == "+" && sign2 == "/" && sign3 == "+")
        {
            finalResult = operand1 + (operand2 / operand3) + operand4;
        }
        if (sign1 == "+" && sign2 == "-" && sign3 == "+")
        {
            finalResult = operand1 + operand2 - operand3 + operand4;
        }


        //---------Subtraction Combinations---------
        if (sign1 == "-" && sign2 == "/" && sign3 == "/")
        {
            finalResult = (operand1 - operand2) / (operand3 / operand4);
        }
        if (sign1 == "-" && sign2 == "+" && sign3 == "+")
        {
            finalResult = operand1 - operand2 + operand3 + operand4;
        }
        if (sign1 == "-" && sign2 == "*" && sign3 == "*")
        {
            finalResult = operand1 - (operand2 * operand3) * operand4;
        }
        //---------
        if (sign1 == "-" && sign2 == "-" && sign3 == "*")
        {
            finalResult = operand1 - operand2 - (operand3 * operand4);
        }
        if (sign1 == "-" && sign2 == "-" && sign3 == "/")
        {
            finalResult = operand1 - operand2 - (operand3 / operand4);
        }
        if (sign1 == "-" && sign2 == "-" && sign3 == "+")
        {
            finalResult = operand1 - operand2 - operand3 + operand4;
        }
        //-----------

        if (sign1 == "-" && sign2 == "*" && sign3 == "-")
        {
            finalResult = operand1 - (operand2 * operand3) - operand4;
        }
        if (sign1 == "-" && sign2 == "/" && sign3 == "-")
        {
            finalResult = operand1 - (operand2 / operand3) - operand4;
        }
        if (sign1 == "-" && sign2 == "+" && sign3 == "-")
        {
            finalResult = operand1 - operand2 + operand3 - operand4;
        }

        //---------Multiplication Combinations---------
        if (sign1 == "*" && sign2 == "/" && sign3 == "/")
        {
            finalResult = (operand1 * operand2) / operand3 / operand4;
        }
        if (sign1 == "*" && sign2 == "+" && sign3 == "+")
        {
            finalResult = (operand1 * operand2) + operand3 + operand4;
        }
        if (sign1 == "*" && sign2 == "-" && sign3 == "-")
        {
            finalResult = (operand1 * operand2) - operand3 - operand4;
        }
        //---------
        if (sign1 == "*" && sign2 == "*" && sign3 == "-")
        {
            finalResult = (operand1 * operand2) * operand3 - operand4;
        }
        if (sign1 == "*" && sign2 == "*" && sign3 == "/")
        {
            finalResult = (operand1 * operand2) * (operand3 / operand4);
        }
        if (sign1 == "*" && sign2 == "*" && sign3 == "+")
        {
            finalResult = (operand1 * operand2) *  (operand3 + operand4);
        }
        //-----------

        if (sign1 == "*" && sign2 == "-" && sign3 == "*")
        {
            finalResult = (operand1 * operand2) - (operand3 * operand4);
        }
        if (sign1 == "*" && sign2 == "/" && sign3 == "*")
        {
            finalResult = (operand1 * operand2) / (operand3 * operand4);
        }
        if (sign1 == "*" && sign2 == "+" && sign3 == "*")
        {
            finalResult = (operand1 * operand2) + (operand3 * operand4);
        }

        //---------Division Combinations---------
        if (sign1 == "/" && sign2 == "*" && sign3 == "*")
        {
            finalResult = (operand1 / operand2) * operand3 * operand4;
        }
        if (sign1 == "/" && sign2 == "+" && sign3 == "+")
        {
            finalResult = (operand1 / operand2) + operand3 + operand4;
        }
        if (sign1 == "/" && sign2 == "-" && sign3 == "-")
        {
            finalResult = (operand1 / operand2) - operand3 - operand4;
        }

        //---------
        if (sign1 == "/" && sign2 == "/" && sign3 == "-")
        {
            finalResult = (operand1 / operand2) / (operand3 - operand4);
        }
        if (sign1 == "/" && sign2 == "/" && sign3 == "*")
        {
            finalResult = (operand1 / operand2) / (operand3 * operand4);
        }
        if (sign1 == "/" && sign2 == "/" && sign3 == "+")
        {
            finalResult = (operand1 / operand2) / (operand3 + operand4);
        }
        //-----------

        if (sign1 == "/" && sign2 == "-" && sign3 == "/")
        {
            finalResult = (operand1 / operand2) - (operand3 / operand4);
        }
        if (sign1 == "/" && sign2 == "*" && sign3 == "/")
        {
            finalResult = (operand1 / operand2) * (operand3 / operand4);
        }
        if (sign1 == "/" && sign2 == "+" && sign3 == "/")
        {
            finalResult = (operand1 / operand2) + (operand3 / operand4);
        }

        //--------if only 3 signs and 4 operands -------------
        equationText.text = operand1 + " " + sign1 + " " + operand2 + " " + sign2 + " " + operand3 +" " + sign3 + " " + operand4 + " " + "= " + finalResult;
    }


}
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11
  • \$\begingroup\$ What is Random.Range? Is this something you wrote yourself or is this a unity API? \$\endgroup\$
    – t3chb0t
    Jul 1, 2017 at 17:59
  • \$\begingroup\$ Random.range is unity API \$\endgroup\$
    – BigDuke6
    Jul 1, 2017 at 19:31
  • \$\begingroup\$ I think the algorithm is simply bad. Make two stacks, one of n operands and one and one of n-1 random operators. pop operands and operators, apply the math, push the result back on the operand stack. continue until the operator stack is empty. This is a 20 line program. \$\endgroup\$
    – Tony Ennis
    Jul 1, 2017 at 22:10
  • \$\begingroup\$ Whenever you see that much repetition, there's something wrong. \$\endgroup\$
    – Stephen S
    Jul 1, 2017 at 22:47
  • \$\begingroup\$ @TonyEnnis Would you care to post your 20 line solution? \$\endgroup\$
    – paparazzo
    Jul 3, 2017 at 20:02

2 Answers 2

Reset to default
3
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What is the purpose of operandList? All you use is the count and that is numberOFOperands.

Just take two passes and do / * in the first pass.

Use a List rather than operand1 - operand5

Use a List rather than sign1 - sign5

I'm not sure this is correct but something like this. 

public static float Maths2(out string equation)
{
    Random rand = new Random();
    float answer = 0;
    List<char> operators = new List<char>() { '+', '-', '/', '*' };
    List<int> operatorsThis = new List<int>();
    List<float> operandsThis = new List<float>();
    int operatorsCount = 4;
    int operandsMin = 1;
    int operandsMax = 10;
    StringBuilder sb = new StringBuilder();
    float f;
    List<int> operatorsThisPlusMinus = new List<int>();
    List<float> operandsPlusMinus = new List<float>();

    for (int i = 0; i < operatorsCount; i++)
    {
        f = rand.Next(operandsMin, operandsMax + 1);
        operandsThis.Add(f);
        sb.Append(f.ToString() + " ");

        int r = rand.Next(4);
        operatorsThis.Add(r);
        sb.Append(operators[r] + " ");
    }
    f = rand.Next(operandsMin, operandsMax + 1);
    operandsThis.Add(f);
    sb.Append(f.ToString() + " ");
    equation = sb.ToString();
    Debug.WriteLine(equation);
    f = operandsThis[0];
    for (int i = 0; i < operatorsThis.Count; i++)
    {
        if (operatorsThis[i] < 2)
        {
            operatorsThisPlusMinus.Add(operatorsThis[i]);
            operandsPlusMinus.Add(f);
            f = operandsThis[i + 1];
        }
        else if (operatorsThis[i] == 2)
        {
            f /= operandsThis[i + 1];
        }
        else if (operatorsThis[i] == 3)
        {
            f *= operandsThis[i + 1];
        }
    }
    operandsPlusMinus.Add(f);
    answer = operandsPlusMinus[0];
    for (int i = 0; i < operatorsThisPlusMinus.Count; i++)
    {
        if (operatorsThisPlusMinus[i] == 0)
        {
            answer += operandsPlusMinus[i + 1];
        }
        else if (operatorsThisPlusMinus[i] == 1)
        {
            answer -= operandsPlusMinus[i + 1];
        }
    }
    Debug.WriteLine(answer);
    return answer;
}
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0
-2
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Ok here I got it to multiply and divide with one operator but the result is still wrong when there are more than one operators. I'm still at a loss here I appreciate the help but I just don't know how to correct the order of operations still.

public class Example : MonoBehaviour {

// Use this for initialization
void Start ()
{
    Maths();

}

// Update is called once per frame
void Update () {

}
public static float Maths()
{
    System.Random rand = new System.Random();
    float answer = 0;
    List<char> operators = new List<char>() { '+', '-', '/', '*' };
    List<int> operatorsThis = new List<int>();
    List<float> operands = new List<float>();
    int operatorsCount = 2;
    int operandsMin = 1;
    int operandsMax = 10;
    StringBuilder sb = new StringBuilder();
    float f;
    int r = -1;


    for (int i = 0; i < operatorsCount; i++)
    {
        f = rand.Next(operandsMin, operandsMax + 1);
        operands.Add(f);
        sb.Append(f.ToString() + " ");

         r = rand.Next(4);
         char c = operators[r];
        operatorsThis.Add(r);
        sb.Append(c + " ");



    }
    f = rand.Next(operandsMin, operandsMax + 1);
    operands.Add(f);
    sb.Append(f.ToString() + " ");
    Debug.Log(sb.ToString());
    f = operands[0];
    answer = f;
    int iLast = 0;

    for (int i = 0; i < operatorsThis.Count; i++)
    {
        if (operatorsThis[i] >= 2)
        {
            iLast = i;
            f = operands[i + 1];

            if (operatorsThis[i] == 2)
            {
                answer /= f;

            }
            if (operatorsThis[i] == 3)
            {

                answer *= f;
            }
        }

        if (operatorsThis[i] < 2)
        {
            iLast = i;
            f = operands[i + 1];


            if (operatorsThis[i] == 0)
            {
                answer += f;
            }
            else if (operatorsThis[i] == 1)
            {
                answer -= f;
            }
        }
        else
        {
            if (operatorsThis[i] == 2)
            {
                f /= operands[i + 1];
            }
            else if (operatorsThis[i] == 3)
            {
                f *= operands[i + 1];
            }
            if (i == operatorsThis.Count - 1)
            {
                if (operatorsThis[iLast] == 0)
                {
                    answer += f;
                }
                else if (operatorsThis[iLast] == 1)
                {
                    answer -= f;
                }
            }
        }
    }
    Debug.Log("the Answer is: " + answer);
    return answer;
}

}

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1
  • \$\begingroup\$ or is there a way i can evaluate the string? \$\endgroup\$
    – BigDuke6
    Jul 1, 2017 at 23:02

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