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String was not recognized as a valid DateTime Issue

I have a method,
public static DateTime ToDate(this object value)
{
return DateTime.ParseExact(value.ToString(), "dd.MM.yyyy", CultureInfo.InvariantCulture);
}
When i run this code with this code,
private void button1_Click(object sender, EventArgs e)
{
MessageBox.Show(DateTime.Now.ToDate().ToString());
}
And there is a error on program like this,
String was not recognized as a valid DateTime
How can i solve this problem?
Thanks.

The problem you're having is that your extension method tries to parse the string specifically in the dd.MM.yyyy format. And you're testing your extension method using the DateTime.Now which returns a DateTime in a format of a current culture on your machine (including hours, minutes, etc.), which may may not be in a dd.MM.yyyy format. You can test your extension method as follows: DateTime.Now.ToString("dd.MM.yyyy").ToDate()
However, If I understand correctly what you're trying to do it is better to change the extension method as follows.
public static DateTime ToDate(this string value, string format)
{
return DateTime.ParseExact(value, format, CultureInfo.InvariantCulture);
}
and use it as follows
private void button1_Click(object sender, EventArgs e)
{
// Testing the extension method.
MessageBox.Show(DateTime.Now.ToString("dd.MM.yyyy").ToDate("dd.MM.yyyy").ToString());
}
Or, if you specifically receive a DateTime in dd.MM.yyyy because of the localization it is better to set the culture of your application globally like so.
// Substitute appropriate culture.
Thread.CurrentThread.CurrentUICulture = new CultureInfo("ru-RU");
Thread.CurrentThread.CurrentCulture = new CultureInfo("ru-RU");
That way you will not need your extension method since the DateTime will always be in the correct format.

your first function must be as follow :
public static DateTime ToDate(this object value)
{
string date = value.ToString("dd.MM.yyyy");
DateTime dt = Convert.ToDateTime(date);
return dt;
}

I suggest to use the TryParseExact
Then you choose the date format that you need
For example :
public static DateTime ToDate(this object value)
{
DateTime OutputDate ;
DateTime.TryParseExact(value, "dd.MM.yyyy", System.Globalization.CultureInfo.InvariantCulture, DateTimeStyles.None, out OutputDate);
return OutputDate ?? DateTime.Now ;
}
In the example : the format is "dd.MM.yyyy" and the input date string is value. The OutputDate will take as value the new datetime object and if the instruction fails it will take null.
Please, verify the format of the date and replace it in the example above if you need

C# - String was not recognized as valid datetime

I have the following method in order to verify whether a string is a valid datetime:
public bool isDate(string date)
{
bool check = false;
try
{
DateTime converted_date = Convert.ToDateTime(date);
check = true;
}
catch (Exception)
{
check = false;
}
return check;
}
Now, the exception "String was not recognized as valid datetime" is caught whenever I try to pass a string like this:
"12/31/2013 12:00:00 AM"
I cannot understand why this is happening. Can someone help me solve this please?

Instead of the try/catch block, try the built in TryParse method in the DateTime class. It takes your string as a parameter and if it converts successfully it will place the value in the "result" variable. It returns a boolean value representing whether it worked or not.
public bool isDate(string date)
{
var result = new DateTime();
return DateTime.TryParse(date, out result);
}

Most likely your current culture settings are different from the format date is provided in. You can try specifying the culture explicitly:
CultureInfo culture = new CultureInfo("en-US"); // or whatever culture you want
Convert.ToDateTime(date, culture);

You can also use DateTime.TryParseExact and pass a format string (eg. MM/dd/yy H:mm:ss zzz, see more here) to check if the date has a specific format.

Empty datetime in the report

I face the following problem :
Sometimes the value of my trans_in(DateTime) in my database is :1900-01-01 00:00:00.000
and it appears in my telerik report like this 12:00 AM i want to show the textbox empty instead so i create the following custom method :
public static string NotAttend(DateTime trans_in)
{
if (trans_in == null || trans_in.ToString().Trim() == "1900-01-01 00:00:00.000")
{
return string.Empty;
}
else
return trans_in.ToShortTimeString();
}
and bind the textbox like this :
= OvertimeReports.CustomExpressions.NotAttend(Fields.trans_in)
but this didn't fix my problem still appear 12:00 AM !!

Your trans_in.ToString() would return you the string representation of your DateTime object based on your current culture, its better if you check your DateTime like:
public static string NotAttend(DateTime trans_in)
{
if(trans_in == new DateTime(1900, 1, 1))
{
return string.Empty;
}
else
return trans_in.ToShortTimeString();
}

Try to compare the trans_in with default(new DateTime())
You shouldn't compare a date with a String without formatting it
reference:
http://social.msdn.microsoft.com/Forums/en-US/netfxbcl/thread/d0f4578c-0585-4f38-95be-569a90ebeb21/
edit: i'm seeing here you'd best compare with DateTime.MinValue
Determining whether the new date is the default new DateTime() or not

You can provide a format to your DateTime by using overridden function of DateTime.ToString(). HH means time in 24 HRS where hh means 12 HRS format :
public static string NotAttend(DateTime trans_in)
{
if (trans_in == null ||
trans_in.ToString("yyyy-MM-dd HH:mm:ss.fff") == "1900-01-01 00:00:00.000")
{
return string.Empty;
}
else
return trans_in.ToShortTimeString();
}

The problem what you have here is more of a formatting issue with the .ToString conversion
Try using the specific format you need in the .ToString overload for this
trans_in("yyyy-M-d HH:mm:ss.fff")
So in this HH case you would have it as 00:00 instead of 12:00
A better way would be to compare it as DateTime make a DateTime obj for 1900-1-1 then compare it with trans_in.Date part which would not involve this string formatting issues

Cannot implicitly convert type bool to System.DateTime (C#)

I'm trying to convert a string to datetime to validate if user input is actually a date.
The error I'm getting is:
Cannot implicitly convert type bool to System.DateTime.
I've been looking online for a while and can't find anything specific enough to help me understand.
Code:
public bool is21YearsOfAge(string argument)
{
DateTime _parsedDateArgument;
DateTime convertStringToDate = System.DateTime.TryParse(argument, out >_parsedDateArgument);
if (convertStringToDate > DateTime.Now)
{
//do something
}
}
Thanks in advance.

The TryParse method returns a bool that informs you whether the parse was successful, rather than throwing an exception like the Parse method does. Try doing this:
DateTime convertStringToDate;
bool isDate = DateTime.TryParse(argument, out convertStringToDate);
If argument is a date, convertStringToDate will contain that date as a DateTime.

DateTime.TryParse returns bool to indicate if parsing was successeful. So you should do
System.DateTime.TryParse(argument, out _parsedDateArgument);
DateTime convertStringToDate =_parsedDateArgument

Look at the documentation for DateTime.TryParse - it returns a bool, but has an out parameter for the parsed result:
DateTime dateTime;
bool success = DateTime.TryParse(text, out dateTime);
If success is false, that means the text couldn't be parsed. (So typically at this point you'd display an error to the user.)
You've already got the out parameter - why did you expect to end up with two different DateTime values (one as the return value and one from the out parameter)?
When you get an error like this, always read the documentation as the first step towards diagnosing the problem.

It should be
DateTime convertStringToDate;
if(System.DateTime.TryParse(argument, out convertStringToDate))
{
//Now you will have converted date in convertStringToDate
if (convertStringToDate > DateTime.Now)
{
//do something
}
}
else
{
//argument not have a valid date
}
System.DateTime.TryParse will retrun true if, argument will have a valid date string to convert. and the converted date will be store in its out parameter.

DateTime.TryParse do not return a DateTime value. It returns a bool indicating if it could parse it.
Instead use
DateTime convertStringToDate;
if(DateTime.TryParse(argument, out convertStringToDate)){
//ok value is good
}else{
//Not ok value is not good
}

use this instead,
DateTime _parsedDateArgument;
bool success = System.DateTime.TryParse(argument, out _parsedDateArgument);
Always remember that Tryparse always return boolean.

TryParse returns a bool, use just Parse instead, or assign the out variable to the new you have:
System.DateTime.TryParse(argument, out _parsedDateArgument);
DateTime convertStringToDate = _parsedDateArgument;
or like this:
DateTime convertStringToDate = DateTime.Parse(argument);

add the following namespace
using System.Globalization;
Create object of CultureInfo class
CultureInfo MyCI = new CultureInfo("en-US");
DateTime convertStringToDate = System.DateTime.TryParse(argument.ToString("MM/dd/yy", MyCI), out _parsedDateArgument);

How to convert dates without getting 'String was not recognized as a valid DateTime.'-error?

I'm trying to convert dates for example 30/12/2000 to 2000-12-30
using this code:
System.Globalization.CultureInfo enUS = new System.Globalization.CultureInfo("en-US");
DateTime.ParseExact(row.Cells[6].ToString(), "yyyy-MM-dd", enUS);
But I'm getting this error:
String was not recognized as a valid DateTime.
Can someone help me please, Thank you in advance.

You could use DateTime.TryParse() function and check if result is true or false.
So you could try to parse date with a specified format and, if its not right, try another one and so on...

The reason why you are getting this is exactly as the exception says, the string is in an incorrect format, the reason is most likely that the machine doing the comparison has a different date time setting to yyyy-MM-dd.
If you are retrieving this from a database and the return value is of date time (or if you know that row.Cells[6] is a DateTime Field, the following should work:
System.Globalization.CultureInfo enUS = new System.Globalization.CultureInfo("en-US");
if (row.Cells[6] != null)
DateTime.ParseExact(((DateTime)row.Cells[6]).ToString("yyyy-MM-dd"), "yyyy-MM-dd", enUS);
The question is however why would you want to change the format, to display it on a form if so then you can just display it as follows:
if (row.Cells[6] != null)
TextBox1.Text = ((DateTime)row.Cells[6]).ToString("yyyy-MM-dd");
EDIT
Given that row.Cells[6] is a string, you will always have to know what the format of the string is, and if you do then it would be as simple as:
With time:
DateTime ParsedDate = DateTime.ParseExact(row.Cells[6].ToString(), "dd-MM-yyyy h:mm", enUS);
Removing time and then parsing:
DateTime ParsedDate = DateTime.ParseExact(row.Cells[6].ToString().Substring(0,10), "dd/MM/yyyy", enUS);
and then to output it in the format you want would be as simple as:
TextBox1.Text = ParsedDate.ToString("yyyy-MM-dd");

You are specifying a en-US CultureInfo object, but 30/12/2000 is not a correct US date format

Try this may resolve your issue
String oldScheduledDate = "16-05-2011";
DateFormat oldFormatter = new SimpleDateFormat("dd/MM/yyyy");
DateFormat formatter = new SimpleDateFormat("yyyy/MM/dd");
try
{
Date oldDate = (Date)oldFormatter .parse(oldScheduledDate);
}
Catch(Exception ex ) { /// process exception}

System.Globalization.CultureInfo enUS = new System.Globalization.CultureInfo("en-US");
try {
DateTime.ParseExact(row.Cells[6].ToString(), "yyyy-MM-dd", enUS);
}
catch (FormatException) {
...your code instead of error...
}

I believe that the problem is your second parameter. If you are passing 30/12/200 as your input, it will fail because the second parameter is expecting it separated with dashes.

use
System.Globalization.CultureInfo.InvariantCulture
DateTime.ParseExact(((DateTime)row.Cells[6]).ToString("yyyy-MM-dd"), "yyyy-MM-dd", System.Globalization.CultureInfo.InvariantCulture)
;

you forgot the hours / minutes:
from the DB it comes like that (converted to string) "12/05/2011 0:00"
DateTime.ParseExact(theCellValue, "MM/dd/yyyy HH:mm", enUS).ToString("yyyy-MM-dd")
creates the string you want, but its totally stupid. you should just make sure that the datetime gets in the first place formatted as you want. (then you never have to parse it)

If your source string is in dd/MM/yyyy, then you shouldn't be using US culture (MM/dd/yyyy) to parse the string.
System.Globalization.CultureInfo enGB = new System.Globalization.CultureInfo("en-GB");
DateTime temp = DateTime.ParseExact(row.Cells[6].Text, "dd/MM/yyyy", enGB);
row.Cells[6] = temp.ToString("yyyy-MM-dd");
Put this in the RowDataBound event of your grid.

I fixed it by using
Convert.ToDateTime(row.Cells[6].Text)
See how simple it is.