TimeOnly

TimeOnly is a value type in the .NET framework that represents a time of day without an associated date. Introduced with DateOnly and TimeOnly to separate concerns between date and time, TimeOnly is part of the System namespace and is commonly used in scheduling, calendars, and any scenario where only the time portion matters.

TimeOnly stores hours, minutes, seconds, and fractional seconds within a 24-hour day. Its practical range spans from 00:00:00.0000000 to 23:59:59.9999999. The type is immutable and designed to be easy to compare, format, and convert with other time-related types.

Creation and conversion: TimeOnly can be constructed directly, or derived from a DateTime or TimeSpan. It can also be created from a TimeSpan that represents the elapsed time since midnight. For interoperability with date components, a DateOnly value can be combined with a TimeOnly to form a full DateTime via a ToDateTime operation on DateOnly.

Formatting and parsing: TimeOnly supports standard and custom formatting strings for displaying times, and it can be parsed from strings using parsing methods with robust error handling (such as TryParse and ParseExact variants). Accessors provide the individual components such as Hour, Minute, Second, and Millisecond.

Operations and usage: TimeOnly supports comparisons and basic arithmetic with TimeSpan values, enabling operations like adding or subtracting time intervals without tying the result to a specific date. This makes TimeOnly a convenient tool for time-of-day calculations, scheduling logic, and user-facing time inputs.

Availability and context: TimeOnly is part of .NET 6 and later, reflecting a broader design goal to reduce misuse of DateTime when only a time-of-day is required.