QDate

QDate is a date-handling class in the Qt Core module used to represent a calendar date without time. It stores dates using the proleptic Gregorian calendar and is independent of time zones, making it suitable for calendar computations, scheduling, and date comparisons. QDate provides validity checks, arithmetic operations, and formatting utilities, supporting both programmatic calculations and user-facing representations.

Constructors and creation functions include a default constructor that creates a null date, a constructor taking year, month, and day, and a copy constructor. Static helpers include currentDate() for obtaining the system’s current date, and fromString(string, format) for parsing textual dates. There is also fromJulianDay(int) to construct a date from a Julian day value.

Key accessors and properties exposed by QDate include year(), month(), and day() to retrieve components of the date, along with dayOfWeek() and dayOfYear() for calendar-related information. Validation methods such as isNull() and isValid() indicate the status of the date. QDate supports comparisons and arithmetic, with daysTo(const QDate&) returning the difference in days between two dates.

Modification and conversion utilities include addDays(int), addMonths(int), and addYears(int), which return new QDate objects with the specified adjustments. For conversions, toJulianDay() yields the corresponding Julian day. Formatting and parsing are supported via toString() (default format) and toString(const QString &format) for custom formats; parsing is complemented by fromString().

In practice, QDate is commonly used alongside QDateTime and QLocale to display localized dates, perform date arithmetic, and drive calendar-based features in Qt applications. See also QDateTime and QLocale.