将字符串转换为双精度时出错 [英] Error in convert string to double

问题描述

将字符串转换为double时出现错误.

看到我的代码
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Hi,

I got error from when i convert string to double.

see my code
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Dim week As String = getWeek(DateTime.Now) ''To get current week
week = Convert.ToDouble(week).ToString '' To convert string to double
Dim Cntweek As String = week & "-" + DateTime.Now.Year ''need to display "28-2011"

但是，在CntWeek中遇到转换错误...吗?

But, getting conversion error in CntWeek...?

推荐答案

这样做:

Do it like this :

Dim week As String = getWeek(DateTime.Now) 'To get current week
week = Convert.ToDouble(week).ToString 
Dim Cntweek As String = week & "-" & DateTime.Now.Year.ToString() 'need to display "28-2011"

更新: 曼弗雷德(Manfred)关于第二行有一个有趣的发现.您可能不需要它.如果您确实需要使用第二行，请再次检查.

Update: There is an interesting observation made by Manfred regarding the second line. You may not be needing it. Please do check again if you really need to use the second line.

为什么您不能以这种方式获得当前星期:

Why don''t you get the current week this way:

Dim week as Integer = Convert.ToInt32(Math.Ceiling(Convert.ToDouble(DateTime.Now.DayOfYear) / 7)
Dim CntWeek as String = string.Format("{0} - {1}", week, DateTime.Now.Year)

编辑=============

我将像这样创建一个扩展方法(这是C#，但应该易于转换为VB).然后，您可以将其用于您希望的任何日期，而不仅仅是今天的日期:

EDIT =============

I would create an extension method like so (this is C#, but shouldbe easy to convert to VB). Then you could use it for any date you wish instead of just today''s date:

public static int WeekOfYear(this DateTime date)
{
    int week = (int)Math.Ceiling((double)date.DayOfYear / 7);
    return week;
}

Dim week As String = getWeek(DateTime.Now)
Dim Cntweek As String = String.Format('{0}-{1}', week, DateTime.Now.Year)

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