TQDate Class

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# TQDate Class Reference

The TQDate class provides date functions. More...

All the functions in this class are reentrant when TQt is built with thread support.

`#include <tqdatetime.h>`

List of all member functions.

## Public Members

- TQDate ()
- TQDate ( int y, int m, int d )
- bool isNull () const
- bool isValid () const
- int year () const
- int month () const
- int day () const
- int dayOfWeek () const
- int dayOfYear () const
- int daysInMonth () const
- int daysInYear () const
- int weekNumber ( int * yearNumber = 0 ) const
- TQString toString ( TQt::DateFormat f = TQt::TextDate ) const
- TQString toString ( const TQString & format ) const
- bool setYMD ( int y, int m, int d )
- TQDate addDays ( int ndays ) const
- TQDate addMonths ( int nmonths ) const
- TQDate addYears ( int nyears ) const
- int daysTo ( const TQDate & d ) const
- bool operator== ( const TQDate & d ) const
- bool operator!= ( const TQDate & d ) const
- bool operator< ( const TQDate & d ) const
- bool operator<= ( const TQDate & d ) const
- bool operator> ( const TQDate & d ) const
- bool operator>= ( const TQDate & d ) const

## Static Public Members

- TQString monthName ( int month ) (obsolete)
- TQString dayName ( int weekday ) (obsolete)
- TQString shortMonthName ( int month )
- TQString shortDayName ( int weekday )
- TQString longMonthName ( int month )
- TQString longDayName ( int weekday )
- TQDate currentDate ()
- TQDate currentDate ( TQt::TimeSpec ts )
- TQDate fromString ( const TQString & s, TQt::DateFormat f = TQt::TextDate )
- bool isValid ( int y, int m, int d )
- bool leapYear ( int y )

## Related Functions

- TQDataStream & operator<< ( TQDataStream & s, const TQDate & d )
- TQDataStream & operator>> ( TQDataStream & s, TQDate & d )

## Detailed Description

The TQDate class provides date functions.

A TQDate object contains a calendar date, i.e. year, month, and day numbers, in the modern Western (Gregorian) calendar. It can read the current date from the system clock. It provides functions for comparing dates and for manipulating dates, e.g. by adding a number of days or months or years.

A TQDate object is typically created either by giving the year, month and day numbers explicitly, or by using the static function currentDate(), which creates a TQDate object containing the system clock's date. An explicit date can also be set using setYMD(). The fromString() function returns a TQDate given a string and a date format which is used to interpret the date within the string.

The year(), month(), and day() functions provide access to the year, month, and day numbers. Also, dayOfWeek() and dayOfYear() functions are provided. The same information is provided in textual format by the toString(), shortDayName(), longDayName(), shortMonthName() and longMonthName() functions.

TQDate provides a full set of operators to compare two TQDate objects where smaller means earlier and larger means later.

You can increment (or decrement) a date by a given number of days using addDays(). Similarly you can use addMonths() and addYears(). The daysTo() function returns the number of days between two dates.

The daysInMonth() and daysInYear() functions return how many days there are in this date's month and year, respectively. The leapYear() function indicates whether this date is in a leap year.

Note that TQDate should not be used for date calculations for dates prior to the introduction of the Gregorian calendar. This calendar was adopted by England from the 14th September 1752 (hence this is the earliest valid TQDate), and subsequently by most other Western countries, until 1923.

The end of time is reached around the year 8000, by which time we expect TQt to be obsolete.

See also TQTime, TQDateTime, TQDateEdit, TQDateTimeEdit, and Time and Date.

## Member Function Documentation

### TQDate::TQDate ()

Constructs a null date. Null dates are invalid.

See also isNull() and isValid().

### TQDate::TQDate ( int y, int m, int d )

Constructs a date with year y, month m and day d.

y must be in the range 1752..8000, m must be in the range 1..12, and d must be in the range 1..31.

Warning: If y is in the range 0..99, it is interpreted as 1900..1999.

See also isValid().

### TQDate TQDate::addDays ( int ndays ) const

Returns a TQDate object containing a date ndays later than the date of this object (or earlier if ndays is negative).

See also addMonths(), addYears(), and daysTo().

### TQDate TQDate::addMonths ( int nmonths ) const

Returns a TQDate object containing a date nmonths later than the date of this object (or earlier if nmonths is negative).

See also addDays() and addYears().

### TQDate TQDate::addYears ( int nyears ) const

Returns a TQDate object containing a date nyears later than the date of this object (or earlier if nyears is negative).

See also addDays() and addMonths().

### TQDate TQDate::currentDate ( TQt::TimeSpec ts )`[static]`

Returns the current date, as reported by the system clock, for the TimeSpec ts. The default TimeSpec is LocalTime.

See also TQTime::currentTime(), TQDateTime::currentDateTime(), and TQt::TimeSpec.

Example: dclock/dclock.cpp.

### TQDate TQDate::currentDate ()`[static]`

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Returns the current date, as reported by the system clock.

See also TQTime::currentTime() and TQDateTime::currentDateTime().

### int TQDate::day () const

Returns the day of the month (1..31) of this date.

See also year(), month(), and dayOfWeek().

Example: dclock/dclock.cpp.

### TQString TQDate::dayName ( int weekday )`[static]`

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Use shortDayName() instead.

### int TQDate::dayOfWeek () const

Returns the weekday (Monday=1..Sunday=7) for this date.

See also day() and dayOfYear().

### int TQDate::dayOfYear () const

Returns the day of the year (1..365) for this date.

See also day() and dayOfWeek().

### int TQDate::daysInMonth () const

Returns the number of days in the month (28..31) for this date.

See also day() and daysInYear().

### int TQDate::daysInYear () const

Returns the number of days in the year (365 or 366) for this date.

See also day() and daysInMonth().

### int TQDate::daysTo ( const TQDate & d ) const

Returns the number of days from this date to d (which is negative if d is earlier than this date).

Example:

            TQDate d1( 1995, 5, 17 );  // May 17th 1995
            TQDate d2( 1995, 5, 20 );  // May 20th 1995
            d1.daysTo( d2 );          // returns 3
            d2.daysTo( d1 );          // returns -3

See also addDays().

### TQDate TQDate::fromString ( const TQString & s, TQt::DateFormat f = TQt::TextDate )`[static]`

Returns the TQDate represented by the string s, using the format f, or an invalid date if the string cannot be parsed.

Note for TQt::TextDate: It is recommended that you use the English short month names (e.g. "Jan"). Although localized month names can also be used, they depend on the user's locale settings.

Warning: TQt::LocalDate cannot be used here.

### bool TQDate::isNull () const

Returns true if the date is null; otherwise returns false. A null date is invalid.

See also isValid().

### bool TQDate::isValid () const

Returns true if this date is valid; otherwise returns false.

See also isNull().

### bool TQDate::isValid ( int y, int m, int d )`[static]`

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Returns true if the specified date (year y, month m and day d) is valid; otherwise returns false.

Example:

        TQDate::isValid( 2002, 5, 17 );  // true   May 17th 2002 is valid
        TQDate::isValid( 2002, 2, 30 );  // false  Feb 30th does not exist
        TQDate::isValid( 2004, 2, 29 );  // true   2004 is a leap year
        TQDate::isValid( 1202, 6, 6 );   // false  1202 is pre-Gregorian

Warning: A y value in the range 00..99 is interpreted as 1900..1999.

See also isNull() and setYMD().

### bool TQDate::leapYear ( int y )`[static]`

Returns true if the specified year y is a leap year; otherwise returns false.

### TQString TQDate::longDayName ( int weekday )`[static]`

Returns the long name of the weekday.

1 = "Monday", 2 = "Tuesday", ... 7 = "Sunday"

The day names will be localized according to the system's locale settings.

See also toString(), shortDayName(), shortMonthName(), and longMonthName().

### TQString TQDate::longMonthName ( int month )`[static]`

Returns the long name of the month.

1 = "January", 2 = "February", ... 12 = "December"

The month names will be localized according to the system's locale settings.

See also toString(), shortMonthName(), shortDayName(), and longDayName().

### int TQDate::month () const

Returns the month (January=1..December=12) of this date.

See also year() and day().

Example: dclock/dclock.cpp.

### TQString TQDate::monthName ( int month )`[static]`

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Use shortMonthName() instead.

### bool TQDate::operator!= ( const TQDate & d ) const

Returns true if this date is different from d; otherwise returns false.

### bool TQDate::operator< ( const TQDate & d ) const

Returns true if this date is earlier than d, otherwise returns false.

### bool TQDate::operator<= ( const TQDate & d ) const

Returns true if this date is earlier than or equal to d, otherwise returns false.

### bool TQDate::operator== ( const TQDate & d ) const

Returns true if this date is equal to d; otherwise returns false.

### bool TQDate::operator> ( const TQDate & d ) const

Returns true if this date is later than d, otherwise returns false.

### bool TQDate::operator>= ( const TQDate & d ) const

Returns true if this date is later than or equal to d, otherwise returns false.

### bool TQDate::setYMD ( int y, int m, int d )

Sets the date's year y, month m and day d.

y must be in the range 1752..8000, m must be in the range 1..12, and d must be in the range 1..31.

Warning: If y is in the range 0..99, it is interpreted as 1900..1999.

Returns true if the date is valid; otherwise returns false.

### TQString TQDate::shortDayName ( int weekday )`[static]`

Returns the name of the weekday.

1 = "Mon", 2 = "Tue", ... 7 = "Sun"

The day names will be localized according to the system's locale settings.

See also toString(), shortMonthName(), longMonthName(), and longDayName().

### TQString TQDate::shortMonthName ( int month )`[static]`

Returns the name of the month.

1 = "Jan", 2 = "Feb", ... 12 = "Dec"

The month names will be localized according to the system's locale settings.

See also toString(), longMonthName(), shortDayName(), and longDayName().

### TQString TQDate::toString ( const TQString & format ) const

Returns the date as a string. The format parameter determines the format of the result string.

These expressions may be used:

Expression | Output
--- | ---
d | the day as number without a leading zero (1-31)
dd | the day as number with a leading zero (01-31)
ddd | the abbreviated localized day name (e.g. 'Mon'..'Sun'). Uses TQDate::shortDayName().
dddd | the long localized day name (e.g. 'Monday'..'Sunday'). Uses TQDate::longDayName().
M | the month as number without a leading zero (1-12)
MM | the month as number with a leading zero (01-12)
MMM | the abbreviated localized month name (e.g. 'Jan'..'Dec'). Uses TQDate::shortMonthName().
MMMM | the long localized month name (e.g. 'January'..'December'). Uses TQDate::longMonthName().
yy | the year as two digit number (00-99)
yyyy | the year as four digit number (1752-8000)

All other input characters will be ignored.

Example format strings (assuming that the TQDate is the 20th July 1969):

Format | Result
--- | ---
dd.MM.yyyy | 20.07.1969
ddd MMMM d yy | Sun July 20 69

If the date is an invalid date, then TQString::null will be returned.

See also TQDateTime::toString() and TQTime::toString().

### TQString TQDate::toString ( TQt::DateFormat f = TQt::TextDate ) const

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Returns the date as a string. The f parameter determines the format of the string.

If f is TQt::TextDate, the string format is "Sat May 20 1995" (using the shortDayName() and shortMonthName() functions to generate the string, so the day and month names are locale specific).

If f is TQt::ISODate, the string format corresponds to the ISO 8601 specification for representations of dates, which is YYYY-MM-DD where YYYY is the year, MM is the month of the year (between 01 and 12), and DD is the day of the month between 01 and 31.

If f is TQt::LocalDate, the string format depends on the locale settings of the system.

If the date is an invalid date, then TQString::null will be returned.

See also shortDayName() and shortMonthName().

### int TQDate::weekNumber ( int * yearNumber = 0 ) const

Returns the week number (1 to 53), and stores the year in *yearNumber unless yearNumber is null (the default).

Returns 0 if the date is invalid.

In accordance with ISO 8601, weeks start on Monday and the first Thursday of a year is always in week 1 of that year. Most years have 52 weeks, but some have 53.

*yearNumber is not always the same as year(). For example, 1 January 2000 has week number 52 in the year 1999, and 31 December 2002 has week number 1 in the year 2003.

Copyright (c) 1989 The Regents of the University of California. All rights reserved.

Redistribution and use in source and binary forms are permitted provided that the above copyright notice and this paragraph are duplicated in all such forms and that any documentation, advertising materials, and other materials related to such distribution and use acknowledge that the software was developed by the University of California, Berkeley. The name of the University may not be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

See also isValid().

### int TQDate::year () const

Returns the year (1752..8000) of this date.

See also month() and day().

## Related Functions

### TQDataStream & operator<< ( TQDataStream & s, const TQDate & d )

Writes the date, d, to the data stream, s.

See also Format of the TQDataStream operators.

### TQDataStream & operator>> ( TQDataStream & s, TQDate & d )

Reads a date from the stream s into d.

See also Format of the TQDataStream operators.

This file is part of the TQt toolkit. Copyright © 1995-2007 Trolltech. All Rights Reserved.