C#,运算符'*'不能应用于'double'和'decimal'类型的操作数

这个错误应该是一个简单的错误,但我似乎无法使它工作.问题在于这个相同的代码在程序的早期工作.我没有看到任何理由在这个实例上发送错误而不是之前的四个错误.参考下面的代码,随时提供任何批评,因为它应该让我更好.如果重要,我正在使用Sharp Develop 2.2.

以下是有效代码示例:

void calc2Click(object sender, EventArgs e)
{
    if (!String.IsNullOrEmpty(tb2_fla.Text) & String.IsNullOrEmpty(tb2_e.Text) | String.IsNullOrEmpty(tb2_fla.Text) & String.IsNullOrEmpty(tb2_e.Text) | String.IsNullOrEmpty(tb2_e.Text))
    {
        MessageBox.Show("Enter either kVA and Voltage or FLA and Voltage", "Invalid Data Entry", MessageBoxButtons.OK);
    }       

        if (!String.IsNullOrEmpty(tb2_kva.Text) & !String.IsNullOrEmpty(tb2_e.Text))
    { 
            decimal x, y, z;
            x = decimal.Parse(tb2_kva.Text);      
            y = decimal.Parse(tb2_e.Text);
            z = (x * 1000) / (1.732050808m * y); //the m at the end of the decimal allows for the multiplication of decimals    
            tb2_fla.Text = z.ToString();
            tb2_fla.Text = Math.Round(z,2).ToString();
    }
        else
    {
        if (!String.IsNullOrEmpty(tb2_fla.Text) & !String.IsNullOrEmpty(tb2_e.Text))
    { 
            decimal x, y, z;
            x = decimal.Parse(tb2_fla.Text);      
            y = decimal.Parse(tb2_e.Text);
            z = (x * y * 1.732050808m) / 1000; //the m at the end of the decimal allows for the multiplication of decimals  
            tb2_kva.Text = Math.Round(z,2).ToString();

    }

以下是在此帖子的主题行中发送错误的代码示例:

void Calc4Click(object sender, EventArgs e)
{
        if (!String.IsNullOrEmpty(tb4_fla.Text) && String.IsNullOrEmpty(tb4_e.Text) || String.IsNullOrEmpty(tb4_kw.Text) & String.IsNullOrEmpty(tb4_e.Text) || String.IsNullOrEmpty(tb4_e.Text))
        {   //If values are entered improperly, the following message box will appear
        MessageBox.Show("Enter either FLA and Voltage or kW and Voltage", "Invalid Data Entry", MessageBoxButtons.OK);
        }   


        if (!String.IsNullOrEmpty(tb4_fla.Text)&& !String.IsNullOrEmpty(tb4_e.Text)&& String.IsNullOrEmpty(tb4_kw.Text))
        {//If the user eneters FLA and Voltage calculate for kW

            decimal x, y, z;
            x = decimal.Parse(tb4_fla.Text);
            y = decimal.Parse(tb4_e.Text);
            z = (x*y)*(.8 * 1.732050808m);
            tb4_kw.Text = Math.Round(z,0).ToString();

        }               

        if (!String.IsNullOrEmpty(tb4_kw.Text) && !String.IsNullOrEmpty(tb4_e.Text) && String.IsNullOrEmpty(tb4_fla.Text))
        {;//If the user enters kW and Voltage calculate for FLA
            decimal x, y, z;
            x = decimal.Parse(tb4_kw.Text);
            y = decimal.Parse(tb4_e.Text);
            z = (1000 * x)/(y * 1.732050808m)* .8;
            tb4_fla.Text = Math.Round(z,0).ToString();
        }

    }

我感谢任何帮助.谢谢.

.8m instead of .8