if i have a datetime string in a weird format, such as YYYY##MM##DD HH**M**SS, how can i create a new datetime object base on that? i have read something about the datetimeformatinfoclass but not sure how to get it working..
You can use DateTime.ParseExact, or DateTime.TryParseExact for data which you're not confident in. For example:
using System;
class Test
{
static void Main()
{
string formatString = "yyyy'##'MM'##'dd' 'HH'*'mm'*'ss";
string sampleData = "2010##02##10 07*22*15";
Console.WriteLine(DateTime.ParseExact(sampleData,
formatString,
null));
}
}
The quotes in the format string aren't strictly necessary - this will work too:
string formatString = "yyyy##MM##dd HH*mm*ss";
However, using the quotes means you're being explicit that the characters between the quotes are to be used literally, and not understood as pattern characters - so if you changed "#" to "/" the version using quotes would definitely use "/" whereas the version without would use a culture-specific value.
The null in the call to ParseExact means "use the current culture" - in this case it's unlikely to make much difference, but a commonly useful alternative is CultureInfo.InvariantCulture.
It's unfortunate that there's no way of getting the BCL to parse the format string and retain the information; my own Noda Time project rectifies this situation, and I'm hoping it'll make parsing and formatting a lot faster - but it's far from production-ready at the moment.
You can use DateTime.ParseExact method and pass the format you need.
Related
I have a file-path that's been created from DateTime stamp:
"C:\\Logs\\Tests\\2015\\Mar\\24\\13_32_09\"
Now I am trying to convert my file-path back to DateTime object.
With Regex I can easily remove "C:\\Logs\\Tests\", but now I am assume I need to provide implementation of IFormtProvider to convert 2015\\Mar\\24\\13_32_09\ into a DateTime object, but I haven't come along any similar example of how that's usually done.
Any example, may not be particular solution to my answer, would be helpful.
Thanks
You can use DateTime.ParseExact like:
DateTime dt = DateTime.ParseExact("2015\\Mar\\24\\13_32_09\\",
#"yyyy\\MMM\\dd\\HH_mm_ss\\",
CultureInfo.InvariantCulture);
No, you don't need to create an IFormatProvider at all. The invariant culture is fine for this (assuming the month name is always in English). You can just use DateTime.ParseExact, passing in the appropriate custom format string (quoting the literal characters, either with apostrophes around them or backslashes before them):
var dateTime = DateTime.ParseExact(
text,
#"yyyy'\'MMM'\'dd'\'HH'_'mm'_'ss'\'",
CultureInfo.InvariantCulture);
Note that this assumes the path really does use backslashes... it won't work on Unix as-is. (You might want to canonicalize the directory separators first.)
I have been working on a project, and found an interesting problem:
2.ToString("TE"+"000"); // output = TE000
2.ToString("TR"+"000"); // output = TR002
I also have tried with several strings other than "TE" but all have the same correct output.
Out of curiosity, I am wondering how come this could have happened?
Simply based on Microsoft's documentation, Custom Numeric Format Strings, your strings "TE000" and "TR000" are both custom format strings, but clearly they are parsed differently.
2.ToString("TE000") is just a bug in the formatter; it's going down a buggy path because of the unescaped "E". So it's unexpectedly assuming the whole thing is a literal.
2.ToString("TR000") is being interpreted as an implied "TR" literal plus 3 zero-filled digits for an integer value; therefore, you get "TR002".
If you truly want TE and TR verbatim, the expressions 2.ToString("\"TE\"000") and 2.ToString("\"TR\"000") will accomplish that for you by specifying TE and TR as explicit literals, instead of letting the formatter guess if they are valid format specifiers (and getting it wrong).
The ToString needs to PARSE the format string and understand what to do with it.
Let's take a look to the following examples:
2.ToString("TE000"); //output TE000
2.ToString("E000"); //output 2E+000
2.ToString("0TE000); //output 2TE000
2.ToString("T"); //throws exception
2.ToString("TT"); //output TT
This shows that if the ToString parser can understand at least part of the format, it will assume that the rest is just extra characters to print with it. If the format is invalid for the given number (like when you use a DateTime string format on a number), it will throw an exception. If it can not make sense of the format, it will return the format string itself as the result.
You cannot use a numeric format to achieve a custom format, instead use something like this:
int i = 2;
String.Format("TE{0:X3}", i);
See Custom Numeric Format Strings. The E means the exponent part of the scientific notation of the number. Since 2 is 2E000 in exponential notation, that might explain it.
I have a string date like so:
var sDate = '3/3/2012'
It eventually goes into a DateTime.ParseExact(sDate, "MM/dd/yyyy")
and it fails because of the missing leading zeros.
What's the best way to add the leading zeros?
I know TryParse would have worked but can't refactor at the moment.
What's the best way to add the leading zeros?
Why would you do that? Just use ParseExact with the format it's actually got, which is M/d/yyyy.
The whole point of the format string is to let you declare the format of your data - not to make you change the format of your data.
Note that you can specify multiple patterns with this overload, so you could always pass in both M/d/yyyy and MM/dd/yyyy. I believe M/d/yyyy will work with zero-padded ones anyway though...
Hi for some reason I cant do a string comparison on a date? Take for example:
public List<HireDate> GetHireDate(string anything)
{
List<HireDate> hiredate = hiredates.Where(n =>
string.Equals(n.HireFromDate, anything, StringComparison.CurrentCultureIgnoreCase)
).ToList();
return hiredate;
}
It simply wont work? if I type into a textbox 13/07/2012 which is how its stored it returns a 404 not found???
The output looks like this from a generic list/get request:
<ArrayOfHireDate>
<HireDate>
<HireFromDate>13/07/2012</HireFromDate>
<HireToDate>28/07/2012</HireToDate>
<NumberOfDaysHired>15</NumberOfDaysHired>
</HireDate>
</ArrayOfHireDate>
Is there another way to find a string with a forward slash in it? For instance using / in any of web string comparers does not work it will always throw a 404 not found?
Two things:
1) To put a string in another string, the most common way to do this is using String.Format. That method takes a format string (such as "Date: {0} Time: {1}") and a bunch of arguments. Each occurrence of {0} in the string is replaced by the first argument, {1} by the second, etc.. There are additional options to format the arguments in the string, see for more information the MSDN page on String.Format.
2) If you have an URL and you get a 404 in your application, first verify that the syntax of the URL is correct. Manually try the URL you create in your program directly in your browser, and if it does not work, find out what syntax is actually used to provide the arguments. For example, it might be that a date must be formatted as 13-07-2012 instead of 13/07/2012 for it to work. If so, you can probably solve this by choosing the appropriate CultureInfo.
For any DateTime date object, to format it has a short date using any CultureInfo you want, use an overload of ToString and specify d as the format. For example, using the invariant culture:
var str = date.ToString("d", CultureInfo.InvariantCulture);
Other format strings can be found here.
Why does:
DateTime.Now.ToString("M")
not return the month number? Instead it returns the full month name with the day on it.
Apparently, this is because "M" is also a standard code for the MonthDayPattern. I don't want this...I want to get the month number using "M". Is there a way to turn this off?
According to MSDN, you can use either "%M", "M " or " M" (note: the last two will also include the space in the result) to force M being parsed as the number of month format.
What's happening here is a conflict between standard DateTime format strings and custom format specifiers. The value "M" is ambiguous in that it is both a standard and custom format specifier. The DateTime implementation will choose a standard formatter over a customer formatter in the case of a conflict, hence it is winning here.
The easiest way to remove the ambiguity is to prefix the M with the % char. This char is way of saying the following should be interpreted as a custom formatter
DateTime.Now.ToString("%M");
Why not use
DateTime.Now.Month?
You can also use System.DateTime.Now.Month.ToString(); to accomplish the same thing
You can put an empty string literal in the format to make it a composite format:
DateTime.Now.ToString("''M")
It's worth mentioning that the % prefix is required for any single-character format string when using the DateTime.ToString(string) method, even if that string does not represent one of the built-in format string patterns; I came across this issue when attempting to retrieve the current hour. For example, the code snippet:
DateTime.Now.ToString("h")
will throw a FormatException. Changing the above to:
DateTime.Now.ToString("%h")
gives the current date's hour.
I can only assume the method is looking at the format string's length and deciding whether it represents a built-in or custom format string.