我的计算器不能使用c#控制台应用程序

这可能是一个非常简单的解决方案，但是当它给出3个错误消息时:

The name 'iNum1' does not exist in the current context  
The name 'iNum2' does not exist in the current context  
The name 'soOper' does not exist in the current context 

当我删除最后一行代码时，它可以工作，但没有它我就无法计算它。我希望有人能帮忙。代码如下:

//information
    Console.WriteLine("This is a calculator");
    //Let them fill in the first number
    Console.WriteLine("Please enter the first number");
    bool bNoNum1 = true;
    while (bNoNum1)
    {
        string sNum1 = Console.ReadLine();
        try
        {
            int iNum1 = int.Parse(sNum1);
            bNoNum1 = false;
        }
        catch (Exception)
        {
            Console.WriteLine("That's not a number");
        }
    }

    //Let them fill in (*, +, / of -)
    Console.WriteLine("Please enter +, +, - or :");
    bool bNoOperator = true;

    do
    {
        string sOper = Console.ReadLine();
        if (sOper == "x")
        {
            string soOper = "*";
            bNoOperator = false;
        }
        else if (sOper == ":")
        {
            string soOper = "/";
            bNoOperator = false;
        }
        else if (sOper == "+")
        {
            string soOper = "+";
            bNoOperator = false;
        }
        else if (sOper == "-")
        {
            string soOper = "-";
            bNoOperator = false;
        }
        else
        {
            Console.WriteLine("De operator " + sOper + " Is niet bekend. Kies uit +, -, x of :");
        }
    } while (bNoOperator);

    //Enter second number
    Console.WriteLine("Please enter the second number");
    bool bNoNum2 = true;
    while (bNoNum2)
    {
        string sNum2 = Console.ReadLine();
        try
        {
            int iNum2 = int.Parse(sNum2);
            bNoNum2 = false;
        }
        catch (Exception)
        {
            Console.WriteLine("That's not a number");
        }
    }
    //calculating
    int uitkomst = iNum1 + soOper + iNum2;