how to dynamically generate a formula and solive it by selecting multiple rows using linq

Question

hi guys i have an array called tblCeMaintMatrix.ToArray()) with a result of :

[0]: { xValue = 0, Operator = 43 '+' }
[1]: { xValue = 1, Operator = 43 '+' }
[2]: { xValue = 12, Operator = 45 '-' }

i made a foreach loop to solve this however i encountered some errors. I think i confused the logic for this..

foreach (var a in tblCeMaintMatrix.ToArray())
{
    {
        value = operate((a.Operator).ToString(),a.xValue.Value );
    }
    decimal value2 = value;
}

private decimal operate(String a, Decimal value)
{
        Decimal Value = 0;
        if (a == "+")
        {
            Value = value + value;
        }

        if (a == "-")
        {
            Value= value - value;
        }

        if (a == "*")
        {
            Value = value * value;
        }

        if (a == "/")
        {
            Value = value / value;
        }

        return Value;
    }

my problem is that

a) what is does is this :

0 + 0 = 0

1 + 1 = 2

12 - 12 = 0

instead of 0 + 1 -12.

b) it doesnt retain the value.

how can i modify this to solve the problem? thanks

Answer 1

Non-tested code, I wish it's correct..

decimal result = 0;

foreach (var a in tblCeMaintMatrix.ToArray())
{
    {
        result = operate((a.Operator).ToString(),a.xValue.Value,result);
    }
}

private decimal operate(String a, Decimal value, Decimal result)
{
     switch (a)
     {
         case "+": result += value; break;
         case "-": result -= value; break;
         case "*": result *= value; break;
         case "/": result /= value; break;
         default: result = value; break;
     }         

     return result;
 }

EDIT to ignore the first operator, I think you need to set your first operator to empty, like:

[0]: { xValue = 0, Operator = '' }
[1]: { xValue = 1, Operator = 43 '+' }
[2]: { xValue = 12, Operator = 45 '-' }

and see the modified Operate method.

Answer 2

Right now you are only passing a single value to your operate method, and using it as both operands. You need to also pass the running total of your code to the function:

Decimal total = 0;
foreach (var a in tblCeMaintMatrix.ToArray())
{
    {
        total = operate((a.Operator).ToString(),total, a.xValue.Value );
    }
    decimal value2 = value;
}

private decimal operate(String a, Decimal left, Decimal right)
{
    Decimal Value = 0;
    if (a == "+")
    {
        Value = left + right;
    }

    if (a == "-")
    {
        Value= left - right;
    }

    if (a == "*")
    {
        Value = left * right;
    }

    if (a == "/")
    {
        Value = left / right;
    }

    return Value;
}

It's not clear what's your using value2 to represent in your original function.