文本框值将检查DropDownList值是否存在 [英] textbox value will check DropDownList value is there or not

问题描述

我对textbox.text值检查dropdownlist值检查有问题吗?帮帮我.

i have problem for textbox.text value check dropdownlist value check? help me.

bool tt = Convert.ToBoolean(DropDownList1.Items.FindByText(TextBoxNew.Text));
                if(tt = true)
{
label.text ="name not exist";
}
else
{
label.text ="name exist";
}

无法将类型为"System.Web.UI.WebControls.ListItem"的对象转换为类型为"System.IConvertible"的对象.

Unable to cast object of type ''System.Web.UI.WebControls.ListItem'' to type ''System.IConvertible''.

thanks karthikeyan, bangalore.

推荐答案

女巫行引发了异常吗?

第一个问题:如果语句是incoret，则在比较时必须使用==而不是单个=.像这样:

witch line was it that threw exception?

1st Problem: if statement is incoret, when you compare you must use == instead of a single =. Like this:

if (tt == true)
{
}

第二个问题:FindByText返回为ListItem而不是Text.试试这个:

2nd Problem: FindByText returns as ListItem instead of Text. Try this:

bool tt = Convert.ToBoolean(DropDownList1.Items.FindByText(TextBoxNew.Text).Text);

ps:我不在Visual Studio的后面，所以我不知道答案的正确性

ps: I am not behined Visual studio so i do not know the accuarty of the answer

错误必须在以下行中:

Error must be in this line:

bool tt = Convert.ToBoolean(DropDownList1.Items.FindByText(TextBoxNew.Text));

显然，您正在尝试在下拉列表项的文本上使用布尔转换.不允许.

只需查找文本，如果找不到，则该文本不存在或存在.

Clearly you are trying to use a bool convert on a dropdown listitem''s text. Not allowed.

Just find the text and if you don''t find then it does not exist or else exist.

Hai，
答案是...

Hai ,
Answer is...

protected void Button1_Click(object sender, EventArgs e)
    {
        //bool tt = Convert.ToBoolean(DropDownList1.Items.FindByText(TextBoxNew.Text));
        ListItem tt = DropDownList1.Items.FindByText(TextBoxNew.Text);
        if (tt == null)
        {
            label.Text = "name not exist";
        }
        else
        {
            label.Text = "name exist";
        }
    }

Karthikeyan Bangalore.

Karthikeyan Bangalore.

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