Probably a simple question -
I'm reading in data from a number of files.
My problem is, that when I'm reading in the date from an american file, I parse it like so:
DateSold = DateTime.Parse(t.Date)
This parses the string t.Date into a date format, however it formats the american date to a european date, e.g.
If the date is in the file as 03/01/2011, it is read as the 3rd of January, 2011, when it should be the 1st of March 2011.
Is there a way of doing this so that it formats to the european date?
var dt = DateTime.ParseExact(t.Date, "MM/dd/yyyy", CultureInfo.InvariantCulture);
The DateTime itself has no formatting, it is only when you convert it to or from a string that the format is relevant.
To view your date with American format, you pass the format to the ToString method
string americanFormat = dt.ToString("MM/dd/yyyy");
If you are parsing the date from a file which is specifically a US formatted file then simply pass the US culture information into the parse function as follows;
var usCulture = "en-US";
var dateValue = DateTime.Parse(dateString, new CultureInfo(usCulture, false));
This way you can simply swap out the culture string per different region required for parsing. Also, you no longer have to research the specific datetime format nuances for each culture as .Net will take care of this for you as designed.
Use DateTime.ParseExact or DateTime.TryParseExact when parsing, and specify a format string when you format with ToString too.
Note that there's no such thing as "an American date" after it's been parsed. The DateTime value has no concept of formatting.
It sounds like you're not actually interested in the Parse part so much as the formatting part, e.g.
string formatted = dt.ToString("dd/MM/yyyy", CultureInfo.InvariantCulture);
... but I would recommend that you control both the parsing and formatting explicitly.
If you have different file formats, you'll need to give different format strings when you read each file. How you then format the data is a separate decision.
If you know the format ahead of time, you can use DateTime.ParseExact, using the American format as your format string.
string formatteddate=DateTime.Now.ToString("d") // output: 11/8/2012
string formatteddate=DateTime.Now.ToString("D") // output: Monday, November 08, 2012
string formatteddate=DateTime.Now.ToString("f") // output: Monday, November 08, 2012 3:39 PM
string formatteddate=DateTime.Now.ToString("g") // output: Monday, November 08, 2012 3:39:46 PM
string formatteddate=DateTime.Now.ToString("d") // output: 11/8/2012 3:39 PM
More date-time format in asp.net is given here.
http://dateformat.blogspot.in/2012/09/date-time-format-in-c-aspnet.html
Related
I have a program that do several things.
Two of them is read a date from a txt and rewrite a date in the same txt.
The read of the date is a regex expression like:
[0-9]{2}/[0-9]{2}/[0-9]{4} [0-9]{2}:[0-9]{2}:[0-5]{1}[0-9]{1})
The problem is that my regex expression only works in the format
"DD/MM/YYYY hh:mm:ss" and its impossible to make sure my regex expression can match all system datetime formats.
So, I need to make sure my program run's in every system, regardless the system datetime.now.
For that, i thought about format every system datetime.now, at start, to the format mentioned "DD/MM/YYYY hh:mm:ss".
At the moment i have the following code:
Datetime currentDate = DateTime.ParseExact(DateTime.Now.ToString(), "DD/MM/YYYY hh:mm:ss", CultureInfo.InvariantCulture);
However, when running some tests, using a system date in format "D/M/YYYY h:m:s" i get the error:
"String was not recognized as a valid DateTime."
The problem is that if my date, for example, is "9/27/2019 04:26:46"(M/D/YYYY h:m:s) it can't fit in the format i defined.
Any idea?
Thank you in advance!
You need to use the same format string and culture in every place where you convert the DateTime to string as well. In your sample code, you're doing
DateTime.Now.ToString()
This uses the default culture for the thread, and the default format. Unless assigned otherwise, the thread is probably using the local culture info. Instead, you would want to use the same format and the invariant culture:
DateTime.Now.ToString("dd/MM/yyyy HH:mm:ss", CultureInfo.InvariantCulture);
(note the lowercase "dd". "DD" is not a valid format specifier for date times; these things are case sensitive. Also note the "HH", which gives a 24-hour value, rather than 12-hour)
In practice, just using the invariant culture should be enough for persistence. Cultures already include default datetime formats, so unless you have a specific need to use a different format, why not use the default?
Also note that DateTime doesn't have a format. The format only comes into play when you convert from or to a string. That is the place where you need to ensure the same culture and format is used for both sides of the operation (and that's why for persistence, especially for data shared between different users or computers, you generally want to use the invariant culture).
If you need
to make sure my program run's in every system, regardless the system datetime.now
you can adapt international standard for this, say, ISO 8601.
In order to validate the DateTime, regular expressions like you have are not enough (just imagine leap years), but TryParse does it job:
string source = "2019-09-26T23:45:59";
// Either current culture date and time format or ISO
bool isValid = DateTime.TryParse(
source,
CultureInfo.InvariantCulture,
DateTimeStyles.AssumeLocal,
out var _date);
Or if you want to be more restrictive use TryParseExact:
// ISO only
bool isValid = DateTime.TryParseExact(
source,
"s",
CultureInfo.InvariantCulture,
DateTimeStyles.AssumeLocal,
out var _date);
If you want to represent DateTime.Now in ISO 8601, add "s" standard format string:
string dateAsString = DateTime.Now.ToString("s");
Alas, you can provide a bunch of formats which are able to cope with any date and time formats; a classical example of ambiguous date is
01/02/03 - 01 Feb 2003 (Russia)
01/02/03 - 02 Jan 2003 (USA)
01/02/03 - 03 Feb 2001 (China)
You can alleviate the problem, while providing several formats:
// Here we try to support 4 formats (note different delimeters)
string[] formats = new string[] {
"s", // try ISO first
"dd'.'MM'.'yyyy HH':'mm':'ss", // if failed try Russian
"MM'/'dd'/'yyyy HH':'mm':'ss", // on error have a look at USA
"yyyy'-'MM'-'dd HH':'mm':'ss", // the last hope is Chinese
};
bool isValid = DateTime.TryParse(
source,
formats,
CultureInfo.InvariantCulture,
DateTimeStyles.AssumeLocal,
out var date);
I want to convert date to a specific format (e.g. en-US MM/dd/yyyy) and I am aware about normal method to parse it.
But in my case I'm unaware about the source date format. Source date format is subject to change as per server environment. It can be en-US or en-GB.
e.g. DateTime dt = DateTime.Now;
'dt' can be '27/03/2014' or '03/27/2014'.
How to convert the source date to en-US format if I don't know source date format?
(string format would be fine - MM/dd/yyyy e.g. "03/27/2014").
If you don't know the source format, there is a chance of getting errors while trying to convert. For example, try converting:
05/01/2013
A computer wouldn't be able to identify the date in such a case. It could result in two outputs: 05 Jan, 2013 or 01 May, 2013.
DateTime.Now.toString("yyyy-MM-dd"); //toString(specify format)
try this one
DateTime result;
if (!DateTime.TryParseExact(inputString, "dd/MM/yyyy", out result)
result = DateTime.ParseExact(inputString, "MM/dd/yyyy");
OR
DateTime result;
if (!DateTime.TryParse(inputString, out result)
result = DateTime.ParseExact(inputString, CultureInfo.InvariantCulture, DateTimeStyles.None);
If you know your environment will always be the deciding factor, why not just use that?
Try some variation of the following:
string yourFormat = ... // Whatever is your default format
if(Thread.CurrentThread.CurrentCulture.Name == "en-US")
{
yourFormat = "MM/dd/yyyy";
}
else (if Thread.CurrentThread.CurrentCulture.Name == "en-GB")
{
yourFormat = "dd/MM/yyyy";
}
DateTime d = DateTime.ParseExact(inputString, yourFormat, null)
How to convert the source date to en-US format if I don't know source date format?
You need to know the source date format, only then can you convert it to the required date format.
As wiero has rightly said in the comments "If you have 01/02/2014 depending its 1 February or 2 January. You have to know how to read it".
The default format of the object returned by DateTime.Now will be the one specified in your server setting, check the screenshot below:
Referring to #DarkWanderer's comment in question:
DateTime object has nothing to do with format.
Just needed to convert it to the specific format using ToString("MM/dd/yyyy").
I was using Parse() method to convert but it will not work. BToString() method is surely a way.
This will work: dt.Tostring("MM/dd/yyyy");
Thanks #DarkWanderer.
I am using an API that outputs dates in this format 20120314T130000 .
The date value is 13:00 14 March 2012. How can I parse a Date in this format to a .Net DateTime variable in C#?
Also what is this date format known as?
That's ISO 8601. The '-' separators are optional in this format.
You can't parse it with the normal DateTime.Parse method, but you can use ParseExact:
DateTime.ParseExact(date, "yyyyMMdd'T'HHmmss", CultureInfo.InvariantCulture)
If you have a mix of dates, some with separators and some without, you might need to use a regex to extract the relevant information and then construct the DateTime object.
The international string representation format is (YYYY-MM-DD HH:MM:SS ±HHMM).
e.g. 2010-06-10 21:21:10 -0400
basically the problem I am having is figuring out how to get the difference from GMT.
DateTime dt = new DateTime(2008, 3, 9, 16, 5, 7, 123);
String.Format("{0:yyyy-MM-dd HH:mm:ss ????}", dt);
DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss zzz");
will output:
2010-06-29 08:25:16 -07:00
string isoFormat = inputDateTime.Format("s");
I would go with ISO format.
And the W3C has also a note on the topic: Date and Time Formats.
These are international standards.
You want to use DateTimeOffset.
I think that is shown in the hours. That -4 is the difference from GMT.
Oh I see, sorry misunderstood the question.
How would you format DateTime in international format?
You can use a custom format specifier (there is no standard formats for ISO standard date/time formats).
the problem I am having is figuring out how to get the difference from GMT.
Parse using one of DateTimeOffset's static methods, and then check the Offset property.
Or if you mean, how to include the offset in the string: use DateTimeOffset with the correct timezone and a custom format specifier.
I'd like to convert a bunch of date strings like the following Mon Aug 7 15:32:52 GMT+0900 2007
to
C# datetime objects.
Is there anything built in to the .net framework to do this or will I have to parse the string into date parts?
Many thanks,
You could use:
DateTime.Parse(datestring);
or
DateTime.TryParse(string, IFormatProvider, DateTimeStyles, out DateTime)
Look at the DateTime.Parse method. You can use the DateTimeFormatInfo class as IFormatProvider. There you could specify the format of the date you want to parse.
Im not sure what "date strings like the following" means since seems you forgot to provide a example. But maybe if you try this.
string date = DateTime.Today.ToString("ddd MMM d HH:mm:ss G'M'Tzzz yyyy", CultureInfo.CreateSpecificCulture("en-EN"));
date = date.Remove(date.LastIndexOf(':'), 1);
// Do whatever you want with the date string
// Output looks like Wed Sep 9 00:00:00 GMT+0200 2009
That looks like a simple RFC formatted date, so a straight DateTime.Parse as Ikke said will work and you shouldn't have to provide the format. You can pass a DateTime object as the second argument in the DateTime.TryParse method to see whether it fails or not, as it returns a boolean.