存储基于下拉列表选择的字符串答案

【问题标题】：Store a string based up dropdownlist selection存储基于下拉列表选择的字符串
【发布时间】：2012-02-21 07:01:54
【问题描述】：

基本上，我正在制作一个网络表单，您将在其中填写所有文本框，然后从下拉列表中选择一个类别并点击提交。根据您选择的类别应该决定文本框中的数据存储在哪个字符串中。当涉及到 C# 和 ASP.NET 时，我处于新手级别，我的 if 语句有些问题，但我无法弄清楚如何正确地做到这一点。

代码如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{
string non_fiction;
string fiction;
string self_help;



protected void Page_Load(object sender, EventArgs e)
{


}


protected void Submit_btn_Click(object sender, EventArgs e)
{
    if (Cat_DropDownList.SelectedIndex = 0)
    {
        fiction = "Title: " + Titletxt.Text + " | " + "Description: " + Descriptiontxt.Text + " | " + "Price: " + Pricetxt.Text + " | " + "Quantity: " + Quantitytxt.Text;
    }

    if (Cat_DropDownList.SelectedIndex = 1)
    {
        non_fiction = "Title: " + Titletxt.Text + " | " + "Description: " + Descriptiontxt.Text + " | " + "Price: " + Pricetxt.Text + " | " + "Quantity: " + Quantitytxt.Text;

    }

    if (Cat_DropDownList.SelectedIndex = 2)
    {
        self_help = "Title: " + Titletxt.Text + " | " + "Description: " + Descriptiontxt.Text + " | " + "Price: " + Pricetxt.Text + " | " + "Quantity: " + Quantitytxt.Text;
    }
}
}

另外，为了保存另一篇文章，我需要找到一种方法来存储这些内容，以便我可以调用“完整”字符串并将它们添加到另一个页面上的另一个字符串中。

【问题讨论】：

在if 条件中使用= 而不是== 是语法错误。你没注意到吗？

标签： c# asp.net if-statement store

【解决方案1】：

我要声明

StringBuilder non_fiction = new StringBuilder();
StringBuilder fiction = new StringBuilder();
StringBuilder self_help = new StringBuilder();

StringBuilder[] strings = null;

并将它们用作

protected void Page_Load(object sender, EventArgs e)
{
    strings = new StringBuilder[] { fiction, non_fiction, self_help };
}

protected void Submit_btn_Click(object sender, EventArgs e)
{
    strings[Cat_DropDownList.SelectedIndex].Append("Title: " + Titletxt.Text + " | " + "Description: " + Descriptiontxt.Text + " | " + "Price: " + Pricetxt.Text + " | " + "Quantity: " + Quantitytxt.Text);
}

没有ifs 和switches

【讨论】：

【解决方案2】：

首先，您在 if 条件中缺少 == 运算符。您需要使用 == 运算符进行比较

 if (Cat_DropDownList.SelectedIndex == 0)
    {
        fiction = "Title: " + Titletxt.Text + " | " + "Description: " + Descriptiontxt.Text + " | " + "Price: " + Pricetxt.Text + " | " + "Quantity: " + Quantitytxt.Text;
    }



 if (Cat_DropDownList.SelectedIndex == 1)
    {
        non_fiction = "Title: " + Titletxt.Text + " | " + "Description: " + Descriptiontxt.Text + " | " + "Price: " + Pricetxt.Text + " | " + "Quantity: " + Quantitytxt.Text;

    }

    if (Cat_DropDownList.SelectedIndex == 2)
    {
        self_help = "Title: " + Titletxt.Text + " | " + "Description: " + Descriptiontxt.Text + " | " + "Price: " + Pricetxt.Text + " | " + "Quantity: " + Quantitytxt.Text;
    }

【讨论】：

【解决方案3】：

if (Cat_DropDownList.SelectedIndex = 0)
{
    fiction = "Title: " + Titletxt.Text + " | " + "Description: " + Descriptiontxt.Text + " | " + "Price: " + Pricetxt.Text + " | " + "Quantity: " + Quantitytxt.Text;
}

= 是赋值 - 您想要与 == 进行比较 - 这同样适用于其他 if 语句。还使用string.Format() 会使该语句更具可读性（imo）：

if (Cat_DropDownList.SelectedIndex == 0)
{
    fiction = string.Format("Title: {0} | Description: {1} | Price: {2} | Quantity: {3}", Titletxt.Text, Descriptiontxt.Text, Pricetxt.Text, Quantitytxt.Text);
}

【讨论】：