我如何使我的文本框仅允许数字1-14？

Question

This is what i have so far, but I am obviously getting an error.

try
{
    dblNights = Convert.ToDouble(txtNights.Text);

    if (dblNights > 1 && 14)
    {
    }
    else
    {
        string script = "alert(\"Number of Nights Must be between 1 and 14!\");";
        ScriptManager.RegisterStartupScript(this, GetType(), "ServerControlScript", script, true);
        txtNights.Focus();
    }
}//End Try

catch
{
    string script = "alert(\"Number of Nights Must be an Integer!\");";
    ScriptManager.RegisterStartupScript(this, GetType(), "ServerControlScript", script, true);

    txtNights.Focus();
}//End Catch

I am not quite sure what to do to make show an error box if numbers besides 1-14 are entered. Everything else is working, just not that. What am I doing wrong?

Thank you.

Answer 1

Problem : You are not properly using the Logical AND operator.

This:

       if (dblNights > 1 && 14)
        {

        }

Must be:

       if (dblNights >= 1 && dblNights <= 14)
        {
             /*valid range some thing here*/
        }

EDIT: as suggested by Eric Lippert in comments i would like to show you usage of TryParse .

if you use double.TryParse() you can eliminate the Exceptions which may occur with invalid data.because double.TryParse() method would return the Boolean value true if the conversion is successful otherwise it returns false so that you could avoid try catch blocks.

Try This:

        double dblNights;
        if (double.TryParse(txtNights.Text, out dblNights))
        {
            //conversion is successfull
        }
        else
        {
            //conversion is Failed
        }

Answer 2

I would have used a RangeValidator

http://www.w3schools.com/aspnet/control_rangevalidator.asp

Save's you the trouble of reinventing the wheel. You can set it's Type property to Integer or Double and not have to worry about parsing values just to validate them.

Answer 3

您可以使用html 5

<input type="number" min="1" max="14" />