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How to Convert date into String format to Date format in C#?

I am trying to convert this ("2019-09-09"(yyyy-MM-dd)) string into date format. I am using DateTime.ParseExact method, but it is not giving me the expected output.
string transactionDateFrom = "2019-09-09";
var provider = CultureInfo.InvariantCulture;
var c = DateTime.ParseExact(transactionDateFrom, "yyyy-MM-dd", provider);
But it shows output as (09/09/2019 12:12Am) I just need format like (yyyy-MM-dd) and it must be date format not string.

You should also provide format for ToString or whenever you use that, since right now you only use it for parsing.
You may also just edit the culture the following way:
CultureInfo culture = (CultureInfo) CultureInfo.CurrentCulture.Clone();
culture.DateTimeFormat.ShortDatePattern = "yyyy-MM-dd";
culture.DateTimeFormat.LongTimePattern = "yyyy-MM-dd";

You should either use DateTime.TryParseExact or use DateTime.TryParse specifying the appropriate CultureInfo.
(For E.g., the culture of the user.)
You can use DateTime.ParseExact method overloads and you can specify exact format and proper (that uses / as a DateSeparator) culture information.
Also be aware that the Difference between M and MM specifiers.
For single digit month numbers, MM specifier will generate month number with leading zero (like 09) but M specifier won't.
string strDate = "2019-09-28";
DateTime date = DateTime.ParseExact(strDate, "yyyy-MM-dd", System.Globalization.CultureInfo.InvariantCulture);
string Format = date.ToString("yyyy-MM-dd", CultureInfo.InvariantCulture);
OR
string strDate = "2019-9-28";
DateTime date = DateTime.ParseExact(strDate, "yyyy-M-dd", System.Globalization.CultureInfo.InvariantCulture);
string Format = date.ToString("yyyy-M-dd", CultureInfo.InvariantCulture);

Convert english Date with parse exact

I try to convert a english date to an german, but my format is not good.
Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");
DateTime currentCultureDate = DateTime.Now;
string format = "dd.MM.yyyy HH:mm:ss";
Console.WriteLine("Format: " + format);
Console.WriteLine("Original Date: " + currentCultureDate);
DateTime convertedDate = DateTime.ParseExact(currentCultureDate.ToString(), format, new CultureInfo("de-DE"));
Console.WriteLine("Converted Date: " + convertedDate);
FormatException.....

DateTime.ParseExact is used to create a DateTime from a string. You can pass a DateTimeFormat or CultureInfo which will be used to convert that string to DateTime.
The method does not convert it to a string in another CultureInfo, say de-DE. Therefore you can use DateTime.ToString:
string germanFormat = DateTime.Now.ToString("dd.MM.yyyy HH:mm:ss", new CultureInfo("de-DE"));

You are not doing what you say: Your code actually tries to parse the date in German format:
// This is German format
string format = "dd.MM.yyyy HH:mm:ss";
// This takes a date and parses it using the ABOVE FORMAT - which is German
DateTime convertedDate = DateTime.ParseExact(currentCultureDate.ToString(), format, new CultureInfo("de-DE"));
If you already have a DateTime you want to output in German format, you don't need ParseExact, but ToString:
string german = DateTime.Now.ToString(format, new CultureInfo("de-DE"));
A DateTime itself doesn't have any culture formatting attached. It is just a date and a time. Only when you output a DateTime, it somehow needs to be converted into a string and to do so, culture information is required. So the rule of thumb is:
If you get a string that represents a date and time value, you need to parse it into a DateTime, either using a fixed format and ParseExact or relying on the framework, passing the source culture information to Parse or TryParse.
If you have a DateTime and want to output it, you need to format it using ToString, providing either a fixed format string and culture information, or use ToString only for the current thread's culture.

How to Convert a Date String with Format "dd/MM/yyyy" to OS Current Culture Date Format

A string has the value in "dd/MM/yyyy" format like "04/10/2012". This should be converted to a Date w.r.t Current Culture of OS.
I have tried below string with Korean as Current Culture of OS in which date format is yyyy-MM-dd, my code is not getting correct Month value, it interchange the month value with day:
Input: "04/10/2012"
Output: 2012-04-10
Code:
DateTime DT;
string dt = "04/10/2012";
DateTimeFormatInfo DateInfo = CultureInfo.CurrentCulture.DateTimeFormat;
DT = Convert.ToDateTime(String.Format ("{0:"+DateInfo .ShortDatePattern +"}", dt.Trim ()), CultureInfo .CurrentCulture);
MessageBox.Show("Date: " + DT.ToShortDateString());
How I can fix that ?

It looks to me like you need to parse it with a fixed format, I think you are currently parsing it with a format other than "dd/MM/yyyy" and because the date is ambiguous (as in, month and day can be interchanged without causing invalid dates) the format is simply switching the month and day value. When you then go to output it, it looks reversed.
Use DateTime.ParseExact to force the parsing format and then use the built-in current culture sensitive string output methods on DateTime to get a formatted string:
var date = DateTime.ParseExact("04/10/2012", "dd/MM/yyyy", CultureInfo.InvariantCulture);
MessageBox.Show("Date: " + date.ToShortDateString()); // Assumes current culture is controlling format

Since your input string is in a fixed format, you should parse it in that format:
DateTime.ParseExact(dt, "dd/MM/yyyy", CultureInfo.InvariantCulture);

If you string has the format dd/MM/yyyy then you have to use DateTime.ParseExact with the specified format:
DateTime.ParseExact(dt, "dd/MM/yyyy", CultureInfo.InvariantCulture);
Anything else will try an interpret the string according to the current culture's rules - which, as you have found, will fail.

why not use ToShortDateTimeString()

How to convert any date format to yyyy-MM-dd

My app parses a string data, extracts the date and identify the format of the date and convert it to yyyy-MM-dd.
The source date could be anything lime dd-mm-yyyy, dd/mm/yyyy, mm-dd-yyyy, mm/dd/yyyy or even yyyy-MM-dd.
Other than attempting different permutations and combinations using switch case, is there any other efficient way to do it?
string sourceDate = "31-08-2012";
String.Format("{0:yyyy-MM-dd}", sourceDate);
The above code simply returns the same sourceDate "31-08-2012".

string DateString = "11/12/2009";
IFormatProvider culture = new CultureInfo("en-US", true);
DateTime dateVal = DateTime.ParseExact(DateString, "yyyy-MM-dd", culture);
These Links might also Help you
DateTime.ToString() Patterns
String Format for DateTime [C#]

Convert your string to DateTime and then use DateTime.ToString("yyyy-MM-dd");
DateTime temp = DateTime.ParseExact(sourceDate, "dd-MM-yyyy", CultureInfo.InvariantCulture);
string str = temp.ToString("yyyy-MM-dd");

string sourceDateText = "31-08-2012";
DateTime sourceDate = DateTime.Parse(sourceDateText, "dd-MM-yyyy")
string formatted = sourceDate.ToString("yyyy-MM-dd");

You can write your possible date formats in array and parse date as following:
public static void Main(string[] args)
{
string dd = "12/31/2015"; //or 31/12/2015
DateTime startDate;
string[] formats = { "dd/MM/yyyy", "dd/M/yyyy", "d/M/yyyy", "d/MM/yyyy",
"dd/MM/yy", "dd/M/yy", "d/M/yy", "d/MM/yy", "MM/dd/yyyy"};
DateTime.TryParseExact(dd, formats,
System.Globalization.CultureInfo.InvariantCulture,
System.Globalization.DateTimeStyles.None, out startDate);
Console.WriteLine(startDate.ToString("yyyy-MM-dd"));
}

You can change your Date Format From dd/MM/yyyy to yyyy-MM-dd in following way:
string date = DateTime.ParseExact(SourceDate, "dd/MM/yyyy", CultureInfo.InvariantCulture).ToString("yyyy-MM-dd");
Here, SourceDate is variable in which you will get selected date.

You will need to parse the input to a DateTime object and then convert it to any text format you want.
If you are not sure what format you will get, you can restrict the user to a fixed format by using validation or datetimePicker, or some other component.

This is your primary problem:
The source date could be anything like dd-mm-yyyy, dd/mm/yyyy,
mm-dd-yyyy, mm/dd/yyyy or even yyyy-MM-dd.
If you're given 01/02/2013, is it Jan 2 or Feb 1? You should solve this problem first and parsing the input will be much easier.
I suggest you take a step back and explore what you are trying to solve in more detail.

Try this code:
lblUDate.Text = DateTime.Parse(ds.Tables[0].Rows[0]["AppMstRealPaidTime"].ToString()).ToString("yyyy-MM-dd");

if (DateTime.TryParse(datetoparser, out dateValue))
{
string formatedDate = dateValue.ToString("yyyy-MM-dd");
}

string sourceDate = "15/06/2021T00.00.00";
DateTime Date = DateTime.Parse(sourceDate)
string date = Date.ToString("yyyy-MM-dd");

Convert.toDateTime(sourceDate).toString("yyyy-MM-dd");

Convert.ToDateTime((string)item["LeaveFromDate"]).ToString("dd/MM/yyyy")
This might be helpful

How can I get date and time formats based on Culture Info?

What I want is..
If culture is en-US then
string dateFormat="MM/dd/yyyy";
string timeFormat="24.00 hrs";
If culture is en-GB then
string dateFormat="dd/mmyyyy";
string timeFormat="24.00 hrs";
and so on for other countries..
Now how do I get these date and time format values ? What are the standards? Like which all countries use similar date/time formats and which ones don't ?
ok I tried this :-
DateTime myDate = new DateTime();
string us = myDate.ToString(new CultureInfo("en-US"));
string us gets value =1/1/0001 12:00:00 AM
Now how do I extract "dd/mm/yyyy" and "24.00 hrs" out of this...in my Dateformat column in my Table... I want to store STRINGS such as dd/mm/yyyy or mm/dd/yyyy NOT dates..In my TimeFormat column in the table, the values to be stores are STRINGS too, like I need to store either "24:00hrs" or "12:00hrs"
How do I do this now ?
**using ShorTimePattern returns these values as
h:mm tt and HH:mm
If I want to store the values in my DB exactly as "24:00hrs" and "12:00hrs", how do I use these values..h:mm tt and HH:mm
which one is for 24 hr format and which for 12 hr format ?**
ok now there's another problem too...I want the information about Decimal Separator and Thousand Separator too based on the CultureInfo...whats the property for that ?

You can retrieve the format strings from the CultureInfo DateTimeFormat property, which is a DateTimeFormatInfo instance. This in turn has properties like ShortDatePattern and ShortTimePattern, containing the format strings:
CultureInfo us = new CultureInfo("en-US");
string shortUsDateFormatString = us.DateTimeFormat.ShortDatePattern;
string shortUsTimeFormatString = us.DateTimeFormat.ShortTimePattern;
CultureInfo uk = new CultureInfo("en-GB");
string shortUkDateFormatString = uk.DateTimeFormat.ShortDatePattern;
string shortUkTimeFormatString = uk.DateTimeFormat.ShortTimePattern;
If you simply want to format the date/time using the CultureInfo, pass it in as your IFormatter when converting the DateTime to a string, using the ToString method:
string us = myDate.ToString(new CultureInfo("en-US"));
string uk = myDate.ToString(new CultureInfo("en-GB"));

// Try this may help
string us = DateTime.Now.Date.ToString("MM/dd/yyyy",new CultureInfo("en-US"));
or
string us = DateTime.Now.Date.ToString("dd/MM/yyyy",new CultureInfo("en-GB"));

You could take a look at the DateTimeFormat property which contains the culture specific formats.

Use a CultureInfo like this, from MSDN:
// Creates a CultureInfo for German in Germany.
CultureInfo ci = new CultureInfo("de-DE");
// Displays dt, formatted using the CultureInfo
Console.WriteLine(dt.ToString(ci));
More info on MSDN. Here is a link of all different cultures.

Try setting a custom CultureInfo for CurrentCulture and CurrentUICulture:
Globalization.CultureInfo customCulture = new Globalization.CultureInfo("en-US", true);
customCulture.DateTimeFormat.ShortDatePattern = "yyyy-MM-dd h:mm tt";
System.Threading.Thread.CurrentThread.CurrentCulture = customCulture;
System.Threading.Thread.CurrentThread.CurrentUICulture = customCulture;
DateTime newDate = System.Convert.ToDateTime(DateTime.Now.ToString("yyyy-MM-dd h:mm tt"));

Culture can be changed for a specific cell in grid view.
<%# DateTime.ParseExact(Eval("contractdate", "{0}"), "MM/dd/yyyy", System.Globalization.CultureInfo.InvariantCulture).ToString("dd/MM/yyyy", System.Globalization.CultureInfo.CurrentCulture) %>
For more detail check the link.
Date Format Issue in Gridview binding with #eval()