Question

我试图用数量的总和来计算 totalAmount 的折扣和 unitPrice 。折扣可以是可选的。可以使用或不使用它取决于用户是否要在折扣文本框中输入一些值。

如果我不打算在其上输入值，我所做的就是将折扣文本框保留为空但我的 totalAmount 仍然为输出提供零值。

 protected void btnCalculate_Click(object sender, EventArgs e)
    {
        double quantity, unitPrice,totalAmount;

        double discount;

        double d;

        bool canProcess = true;

        //Quantity
        if (!double.TryParse(lblQuantity.Text, out quantity))
        { 
            //Conversion Failed
            string script = "alert(\"Quantity cannot be converted\");";

            ScriptManager.RegisterStartupScript(this, GetType(),
                "ServerControlScript", script, true);
        }
        //UnitPrice
        if (!double.TryParse(txtUnitPrice.Text, out unitPrice))
        { 
            //Conversion Failed
            string script = "alert(\"Unit Price cannot be converted\");";

            ScriptManager.RegisterStartupScript(this, GetType(),
                "ServerControlScript", script, true);
        }
        if (!double.TryParse(txtDisc.Text, out discount))
        {
            //Conversion Failed
            string script = "alert(\"discount cannot be converted\");";

            ScriptManager.RegisterStartupScript(this, GetType(),
                "ServerControlScript",script,true);
        }
        if (canProcess)
        {
          d = quantity * unitPrice;

            totalAmount = ((d*discount)/100);
            lblTotalAmount.Text = totalAmount.ToString();
        }
    }
    //#calculator end
}

Answer 1

如果您希望折扣是可选的，请确定您希望如何计算金额：

    if (canProcess)
    {
        d = quantity * unitPrice;

        if(discount == 0)
        {
            totalAmount = d;// any calculation
        }
        else
        {
            totalAmount = ((d*discount)/100);
        }

        lblTotalAmount.Text = totalAmount.ToString();
    }

Answer 2

当然你需要检查第一个折扣大于0，然后你可以计算总金额

if (canProcess)
{
    d = quantity * unitPrice;

    if(discount == 0)
    {
        totalAmount = d;
    }
    else
    {
        totalAmount = ((d*discount)/100);// if here d is 0 your total amt will be 0.
    }

    lblTotalAmount.Text = totalAmount.ToString();
}

可选的折扣文本框给出0值

2 个答案: