将字符串转换为日期时间 [英] Convert a string to a datetime

问题描述

我正在使用 vb 框架3.5 开发 asp.net p>

将字符串数据转换为Date
有困难我尝试使用cdate函数，

我有一个变量sdate是一个字符串变量和日期存储在其中，它以文本框为dd / mm / yyyy，现在我想将此字符串转换为Date变量，因为我需要执行操作作为添加一天或减去一天。

请指导我如何做到这一点。我在第三行出现错误，字符串未被识别为有效的DateTime 。我试图做如下，但错误来了

  Dim sdate As String 
 Dim spenddt As Date 
 spenddt = Date.Parse（edate）
 spenddt = consumdt.AddDays（-1）
  

但是我收到错误为

从字符串转换为类型日期无效。

如何从字符串中获取 Date

解决方案

您应该使用 Date.ParseExact 或 Date.TryParseExact 正确格式字符串。

  Dim edate =10/12/2009
 Dim spenddt As Date = Date.ParseExact ed，dd / MM / yyyy，
 System.Globalization.DateTimeFormatInfo.InvariantInfo）
  

或

  Dim format（）= {dd / MM / yyyy，d / M / yyyy，dd -MM-yyyy} 
 Dim spenddt As Date = Date.ParseExact（edate，format，
 System.Globalizatio n.DateTimeFormatInfo.InvariantInfo，
 Globalization.DateTimeStyles.None）
  

或

  Dim format（）= {dd / MM / yyyy，d / M / yyyy，dd-MM-yyyy} 
 Dim spenddt As Date 
 Date.TryParseExact（edate，format，
 System.Globalization.DateTimeFormatInfo.InvariantInfo，
 Globalization.DateTimeStyles.None，consumdt）
  




I am developing asp.net site using vb framework 3.5.

Im having difficulties converting string data into Date I tried using cdate function,

I have a variable sdate which is a string variable and date is stored in it which comes from textbox as dd/mm/yyyy now i want to convert this string into a Date variable as i need to perform the operations as Add a day or Subtract a day.

Please guide me how to go about this. i get the error on 3rd line as,String was not recognized as a valid DateTime. I have tried to do as follows but the error comes

Dim sdate As String 
Dim expenddt As Date
expenddt = Date.Parse(edate)
expenddt = expenddt.AddDays(-1)

But i get the error as

Conversion from String to type Date is not valid.

How can I get a Date from the string?

解决方案

You should have to use Date.ParseExact or Date.TryParseExact with correct format string.

 Dim edate = "10/12/2009"
 Dim expenddt As Date = Date.ParseExact(edate, "dd/MM/yyyy", 
            System.Globalization.DateTimeFormatInfo.InvariantInfo)

OR

 Dim format() = {"dd/MM/yyyy", "d/M/yyyy", "dd-MM-yyyy"}
 Dim expenddt As Date = Date.ParseExact(edate, format,  
     System.Globalization.DateTimeFormatInfo.InvariantInfo, 
     Globalization.DateTimeStyles.None)

OR

Dim format() = {"dd/MM/yyyy", "d/M/yyyy", "dd-MM-yyyy"}
Dim expenddt As Date
Date.TryParseExact(edate, format, 
    System.Globalization.DateTimeFormatInfo.InvariantInfo, 
    Globalization.DateTimeStyles.None, expenddt)

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