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C# DateTime Not Formatting Correctly to String

I am trying to get the created date and time of a particular file and then format it from 4/9/2016 to 040916. I end up with the result of 56DD16. I am not entirely sure where this value is coming from. I have used this method to format dates before without any problem. The code is below:
FileInfo fi = new FileInfo(Path.Combine(r.getCompanyFilesLocation(), r.getNyseFileName()));
DateTime dateCreated = fi.CreationTime;
string archiveFileName = dateCreated.ToString("mmDDyy");

You are using incorrect format string,mm Represent the Minute and there is nothing for DD, dd stands for day. so Change your formatString as MMddyy. to get the expected output. Here you can find more formatting options
string archiveFileName = dateCreated.ToString("MMddyy");

.ToString("mmDDyy") is incorrect. The format should be .ToString("MMddyy")
You can always review the Custom Date and Time Format Strings.

You were using wrong format. Use this one and you will get the exact same output you required:
DateTime dateCreated = fi.CreationTime;
string archiveFileName = dateCreated.ToString("MMddyy", CultureInfo.InvariantCulture);

Get yesterday's date from the date entered

I have console application that accepts date as parameter. However, the date is passed as a string in this format:
string dt = DateTime.Now.ToString("yyyyMMdd");
Once the date is entered I need to programmatically get day - 1 from the entered date. Since this is a string, I cannot do any calculation.
For example, user enters:
20141023
I need to subtract a day from the date to get:
20141022
I did a quick fix to solve my immediate need, however, this is not the right way to do it and it has a bug:
int yt = Int32.Parse(dt) - 1;
And then I turn around and convert it yt.ToString()
The above solution will not work if it's the 1st of the month.
Is there a way I can programmatically get yesterday's date in the format (yyyyMMdd) without changing the format and possibly not using the TimeSpan?

Why don't parse the input into a DateTime object? Then you can use the DateTime.AddDays(-1)
For example:
var inputDate = DateTime.ParseExact("20141022", "yyyyMMdd", CultureInfo.InvariantCulture); // change "20141022" into the inputted value
var yesterday = inputDate.AddDays(-1);
var yesterdayString = yesterday.ToString("yyyyMMdd"); // this will be yesterdays date, in the string format

Try this...
DateTime data = DateTime.ParseExact("20141023", "yyyyMMdd", CultureInfo.InvariantCulture);
Console.WriteLine("{0} - {1}", data, data.AddDays(-1).ToString("yyyyMMdd"));

Would this work for you ?
string newDateTimeStr = (DateTime.Today.AddDays(-1)).ToString("yyyyMMdd");
EDIT:
for the date entered by the user:
string txtInputDate = Console.ReadLine();
DateTime dateTime = new DateTime(txtInputDate).ToLocalTime();
string newDateTimeStr = (dateTime.AddDays(-1)).ToString("yyyyMMdd");

How to convert dd/mm to Mysql Datetime format in c#

I have a date string with dd/mm format like 06/03.Now i have to store this string into mysql table column with DATETIME format.
I am getting the problem as How can i add the current year generically because i don't want to hard code it.Subsequently how will i convert it into MySql DATETIME format for saving it.
Please help me .

You can use Parse method of DateTime:
DateTime dateTime = DateTime.Parse("06/03");
UPDATE
For your comment:
Also after parsing into DateTime i am getting date correct but time i
dont want to be 12:00:00 AM instead i want it to be 00:00:00.
12:00:00 AM corresponds to 00:00:00 only. You can verify that by getting Hour property which will return 0 and also TimeOfDay will too return 00:00:00.
Even if you try to parse exact date, it also creates the same format.
DateTime dateTime = DateTime.ParseExact("06/03 00:00:00", "dd/MM hh:mm:ss",
CultureInfo.InvariantCulture);
And you don't need conversion from DateTime object to SQL compliant DateTime object. You can pass the .Net object to SQL writer.

Consider the code:
C#
string s = "06/03";
System.DateTime dateNow = Convert.ToDateTime(s);
will give the output as you required
in VB.Net :
Dim s As String = "06/03"
Dim dateNow As Date = CDate(s)
MsgBox(dateNow)

You could do something like
var some_date = "06/03";
var year = DateTime.Now.Year;
var option = some_date+"/"+year;
Or use any of the string formats to bend it to your needs
More on date string format can be found on this MSDN page.
Edit:
If you want zeroes in the time, like your comment said, you can usit Rohit vats answer and do:
DateTime dateTime = DateTime.Parse("06/03");
var s1 = dateTime.ToString("MM/dd/yy 00:00:00");
// Output: 03/06/14 00:00:00
var s2 = dateTime.ToString("MM/dd/yyyy 00:00:00");
// Output: 03/06/2014 00:00:00

Current date without time

How can I get the current date but without the time? I am trying to convert the date from the "dd.mm.yyyy" format to "yyyy-MM-dd", because DateTime.Now returns the time too, I get an error (String was not recognized as a valid DateTime.) when I try to do the following.
string test = DateTime.ParseExact(DateTime.Now.ToString(), "dd.MM.yyyy", CultureInfo.InvariantCulture).ToString("yyyy-MM-dd");

Use the Date property: Gets the date component of this instance.
var dateAndTime = DateTime.Now;
var date = dateAndTime.Date;
variable date contain the date and the time part will be 00:00:00.
or
Console.WriteLine(DateTime.Now.ToString("dd/MM/yyyy"));
or
DateTime.ToShortDateString Method-
Console.WriteLine(DateTime.Now.ToShortDateString ());

String test = DateTime.Now.ToString("dd.MM.yyy");

Have you tried
DateTime.Now.Date

String test = DateTime.Now.ToShortDateString();

it should be as simple as
DateTime.Today

This should work:
string datetime = DateTime.Today.ToString();

You can get current UTC date without time.
string currentDate = DateTime.UtcNow.ToString("yyyy-MM-dd");

As mentioned in several answers already that have been already given, you can use ToShorDateString():
DateTime.Now.ToShortDateString();
However, you may be a bit blocked if you also want to use the culture as a parameter. In this case you can use the ToString() method with the "d" format:
DateTime.Now.ToString("d", CultureInfo.GetCultureInfo("en-US"))

Try this:
var mydtn = DateTime.Today;
var myDt = mydtn.Date;return myDt.ToString("d", CultureInfo.GetCultureInfo("en-US"));

If you need exact your example, you should add format to ToString()
string test = DateTime.ParseExact(DateTime.Now.ToString("dd.MM.yyyy"), "dd.MM.yyyy", CultureInfo.InvariantCulture).ToString("yyyy-MM-dd");
But it's better to use straight formatting:
string test = DateTime.Now.ToString("yyyy-MM-dd")

String was not recognized as a valid DateTime " format dd/MM/yyyy"

I am trying to convert my string formatted value to date type with format dd/MM/yyyy.
this.Text="22/11/2009";
DateTime date = DateTime.Parse(this.Text);
What is the problem ?
It has a second override which asks for IFormatProvider. What is this? Do I need to pass this also? If Yes how to use it for this case?
Edit
What are the differences between Parse and ParseExact?
Edit 2
Both answers of Slaks and Sam are working for me, currently user is giving the input but this will be assured by me that they are valid by using maskTextbox.
Which answer is better considering all aspects like type saftey, performance or something you feel like

Use DateTime.ParseExact.
this.Text="22/11/2009";
DateTime date = DateTime.ParseExact(this.Text, "dd/MM/yyyy", null);

You need to call ParseExact, which parses a date that exactly matches a format that you supply.
For example:
DateTime date = DateTime.ParseExact(this.Text, "dd/MM/yyyy", CultureInfo.InvariantCulture);
The IFormatProvider parameter specifies the culture to use to parse the date.
Unless your string comes from the user, you should pass CultureInfo.InvariantCulture.
If the string does come from the user, you should pass CultureInfo.CurrentCulture, which will use the settings that the user specified in Regional Options in Control Panel.

Parsing a string representation of a DateTime is a tricky thing because different cultures have different date formats. .Net is aware of these date formats and pulls them from your current culture (System.Threading.Thread.CurrentThread.CurrentCulture.DateTimeFormat) when you call DateTime.Parse(this.Text);
For example, the string "22/11/2009" does not match the ShortDatePattern for the United States (en-US) but it does match for France (fr-FR).
Now, you can either call DateTime.ParseExact and pass in the exact format string that you're expecting, or you can pass in an appropriate culture to DateTime.Parse to parse the date.
For example, this will parse your date correctly:
DateTime.Parse( "22/11/2009", CultureInfo.CreateSpecificCulture("fr-FR") );
Of course, you shouldn't just randomly pick France, but something appropriate to your needs.
What you need to figure out is what System.Threading.Thread.CurrentThread.CurrentCulture is set to, and if/why it differs from what you expect.

Although the above solutions are effective, you can also modify the webconfig file with the following...
<configuration>
<system.web>
<globalization culture="en-GB"/>
</system.web>
</configuration>
Ref : Datetime format different on local machine compared to production machine

You might need to specify the culture for that specific date format as in:
Thread.CurrentThread.CurrentCulture = new CultureInfo("en-GB"); //dd/MM/yyyy
this.Text="22/11/2009";
DateTime date = DateTime.Parse(this.Text);
For more details go here:
http://msdn.microsoft.com/en-us/library/5hh873ya.aspx

Based on this reference, the next approach worked for me:
// e.g. format = "dd/MM/yyyy", dateString = "10/07/2017"
var formatInfo = new DateTimeFormatInfo()
{
ShortDatePattern = format
};
date = Convert.ToDateTime(dateString, formatInfo);

After spending lot of time I have solved the problem
string strDate = PreocessDate(data);
string[] dateString = strDate.Split('/');
DateTime enter_date = Convert.ToDateTime(dateString[1]+"/"+dateString[0]+"/"+dateString[2]);

private DateTime ConvertToDateTime(string strDateTime)
{
DateTime dtFinaldate; string sDateTime;
try { dtFinaldate = Convert.ToDateTime(strDateTime); }
catch (Exception e)
{
string[] sDate = strDateTime.Split('/');
sDateTime = sDate[1] + '/' + sDate[0] + '/' + sDate[2];
dtFinaldate = Convert.ToDateTime(sDateTime);
}
return dtFinaldate;
}

use this to convert string to datetime:
Datetime DT = DateTime.ParseExact(STRDATE,"dd/MM/yyyy",System.Globalization.CultureInfo.CurrentUICulture.DateTimeFormat)

Just like someone above said you can send it as a string parameter but it must have this format: '20130121' for example and you can convert it to that format taking it directly from the control. So you'll get it for example from a textbox like:
date = datetextbox.text; // date is going to be something like: "2013-01-21 12:00:00am"
to convert it to: '20130121' you use:
date = date.Substring(6, 4) + date.Substring(3, 2) + date.Substring(0, 2);
so that SQL can convert it and put it into your database.

Worked for me below code:
DateTime date = DateTime.Parse(this.Text, CultureInfo.CreateSpecificCulture("fr-FR"));
Namespace
using System.Globalization;

You can use also
this.Text = "22112009";
DateTime newDateTime = new DateTime(Convert.ToInt32(this.Text.Substring(4, 4)), // Year
Convert.ToInt32(this.Text.Substring(2,2)), // Month
Convert.ToInt32(this.Text.Substring(0,2)));// Day

Also I noticed sometimes if your string has empty space in front or end or any other junk char attached in DateTime value then also we get this error message