ParseExact

ParseExact is a method used in the .NET framework to convert a textual representation of a date and time into a DateTime value by requiring that the input string conform to a specified format exactly. It is commonly used when input must match a predefined pattern, rather than being flexibly parsed.

In .NET, the typical signature is DateTime.ParseExact(string s, string format, IFormatProvider provider), with overloads that accept an array of accepted formats, a DateTimeStyles value, and a provider. The method uses the supplied culture information to interpret culture-specific components such as month names and calendar rules, and it can work with standard or custom format specifiers.

If the input does not match the format, ParseExact throws a FormatException. There is also TryParseExact, which returns a boolean indicating success and outputs the parsed DateTime without throwing exceptions. If the parsed value falls outside the allowable DateTime range, an OverflowException is thrown. DateTimeStyles can be supplied to adjust parsing behavior, such as allowing leading white space, assuming universal time, or adjusting the resulting kind.

Format strings for ParseExact use a mix of standard and custom specifiers, such as yyyy, MM, dd, HH, mm, ss, and K, and may include literals. Escaping or quoting enables including separators or fixed text. For time zones or offsets, DateTimeOffset with ParseExact can be used, or the format can include offset specifiers like zzz. To minimize locale dependence, InvariantCulture is a common provider.

Related concepts include Parse, TryParse, and ParseExact variants for DateTimeOffset and TimeSpan, all used for strict or culture-aware parsing of textual representations.