Software independent of the user's local settings. The CultureInfo.InvariantCulture property is used if you areįormatting or parsing a string that should be parseable by a piece of If you know what specific culture that your dates and decimal /Ĭurrency values will be in ahead of time, you can use that specificĬultureInfo property (i.e. Will also matter if you try to format the aforementioned data types to That are stored as strings to DateTime, float, double or decimal. This will matter for you when you are converting input values (read) Not all cultures use the same format for dates and decimal / currency Spread for ASP. The real purpose of invariant culture is taken taken from a an answer in this question, as it describes it's purpose best: &0183 &32 Creates a new formatter with the specified format and formatting information (copied from the current culture). In order to avoid that you use the wider form of each component. there are other dates which will return the same string. You can easily see that the second one is not unique, i.e. omitting CultureInfo.InvariantCulture for brevityĭt.ToString("yyyyMMddHHmmss") // returns "20180102034506"ĭt.ToString("yyyyMdHms") // returns "2018123456" In order to do that without separators you have to use fixed length strings for each component. The format of the string representation must match the specified format exactly or an exception is thrown. If you use a custom format, then it would surely be good if the resulting string can be parsed back into the exact same date and time. DateTime ParseExact (String, String, IFormatProvider, DateTimeStyles) converts the specified string representation of a date and time to its DateTime equivalent using the specified format, culture-specific format information, and style. On the other hand if you display the date on the screen, you generally respect the user's choice of culture and display it in the preferred way.
#FORMAT AS IFORMAT PROVIDER ISO#
For example in a JSON or XML file you want to store the date in ISO format so there is no ambiguity. Supplies culture-specific formatting information. You should use it every time you format something that is not meant to be parsed by humans. public string ToString( string format, IFormatProvider provider ). The final tip, don't even bother trying to do this stuff from memory without Chris Sells' FormatDesigner.The purpose of InvariantCulture is to have a well-known way to format dates and numbers, that does not depend on the system or user locale. There are similar rules with "MM" for months and "mm" for minutes. Also, remember that "HH" is "zero-prepended 24-hour time" while "H" is "no-zeros 24-hour time" and "hh" and "h" are 12-hour times respectively. String myNewDate = the escaping on the "M" in the string literal "GMT." That's because "M" by itself is a Month formatter, so we say " no seriously, I meant M" by using "\M". TOTALLY OPTIONAL, but worth noting, assuming it was local time It's harder to parse these strings minus a little finger, and while harsh, this kind of punishment should deter others from making the same mistake. This is the height of pure evil and anyone who does it should lose a pinky. Public Function ToString ( format As String, formatProvider As. He had do a (culture senstive) DateTime.ToString() then started parsing it into the specific format he wanted. public string ToString( string format, IFormatProvider formatProvider ). I caught a fellow trying to to a DateTime conversion recently. This should be replaced with a call to (System.IFormatProvider,System.String,System.Object ). makes a call to (System.String,System.Object) that does not explicitly provide an IFormatProvider. Since I used the double (MM) numeric formats, this isn't a problem in 99% of cultures, but I could change calendars inadvertantly in Thai, in the Maldives, or in Saudi Arabia where different calendars are used.ĭo NOT underestimate the power of ToString(IFormatProvider). There is a rule that it is difficult to understand for me. Paul points out that the final call to ToString should use the InvariantCulture, lest I end up with odd characters. First, RichB points out that ':' is a format modifier itself that describes the hours separator . In the comments RichB and Paul van Brenk pointed out two bugs in my solution.
#FORMAT AS IFORMAT PROVIDER UPDATE#
UPDATE: I write this update minus one pinky finger.