The QTime class provides clock time functions. 更多...
| 头： | #include <QTime> |
| qmake: | QT += core |
注意： 此类的所有函数 可重入 .
| QTime () | |
| QTime (int h , int m , int s = 0, int ms = 0) | |
| QTime | addMSecs (int ms ) const |
| QTime | addSecs (int s ) const |
| int | elapsed () const |
| int | hour () const |
| bool | isNull () const |
| bool | isValid () const |
| int | minute () const |
| int | msec () const |
| int | msecsSinceStartOfDay () const |
| int | msecsTo (const QTime & t ) const |
| int | restart () |
| int | second () const |
| int | secsTo (const QTime & t ) const |
| bool | setHMS (int h , int m , int s , int ms = 0) |
| void | start () |
| QString | toString (const QString & format ) const |
| QString | toString (Qt::DateFormat format = Qt::TextDate) const |
| QString | toString (QStringView format ) const |
| bool | operator!= (const QTime & t ) const |
| bool | operator< (const QTime & t ) const |
| bool | operator<= (const QTime & t ) const |
| bool | operator== (const QTime & t ) const |
| bool | operator> (const QTime & t ) const |
| bool | operator>= (const QTime & t ) const |
| QTime | currentTime () |
| QTime | fromMSecsSinceStartOfDay (int msecs ) |
| QTime | fromString (const QString & string , Qt::DateFormat format = Qt::TextDate) |
| QTime | fromString (const QString & string , const QString & format ) |
| bool | isValid (int h , int m , int s , int ms = 0) |
| QDataStream & | operator<< (QDataStream & out , const QTime & time ) |
| QDataStream & | operator>> (QDataStream & in , QTime & time ) |
The QTime class provides clock time functions.
A QTime object contains a clock time, which it can express as the numbers of hours, minutes, seconds, and milliseconds since midnight. It can read the current time from the system clock and measure a span of elapsed time. It provides functions for comparing times and for manipulating a time by adding a number of milliseconds.
QTime uses the 24-hour clock format; it has no concept of AM/PM. Unlike QDateTime , QTime knows nothing about time zones or daylight-saving time (DST).
A QTime object is typically created either by giving the number of hours, minutes, seconds, and milliseconds explicitly, or by using the static function currentTime (), which creates a QTime object that represents the system's local time.
The hour (), minute (), second ()，和 msec () 函数提供对时间的小时、分钟、秒及毫秒数的访问。以正文格式提供相同信息是通过 toString () 函数。
The addSecs () 和 addMSecs () 函数提供晚于给定时间的给定秒 (或毫秒) 数的时间。相应地，查找 2 时间之间的秒 (或毫秒) 数可以使用 secsTo () 或 msecsTo ().
QTime provides a full set of operators to compare two QTime objects; an earlier time is considered smaller than a later one; if A. msecsTo (B) 为正值，那么 A < B。
QTime can be used to measure a span of elapsed time using the start (), restart ()，和 elapsed () 函数。
以字符串形式返回时间。 format 参数确定结果字符串的格式。
这些表达式可以使用：
| 表达式 | 输出 |
|---|---|
| h | the hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display) |
| hh | the hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display) |
| H | the hour without a leading zero (0 to 23, even with AM/PM display) |
| HH | the hour with a leading zero (00 to 23, even with AM/PM display) |
| m | the minute without a leading zero (0 to 59) |
| mm | the minute with a leading zero (00 to 59) |
| s | the whole second, without any leading zero (0 to 59) |
| ss | the whole second, with a leading zero where applicable (00 to 59) |
| z |
the fractional part of the second, to go after a decimal point, without trailing zeroes (0 to 999). Thus "
s.z
" reports the seconds to full available (millisecond) precision without trailing zeroes.
|
| zzz | the fractional part of the second, to millisecond precision, including trailing zeroes where applicable (000 to 999). |
| AP or A | use AM/PM display. A/AP will be replaced by either QLocale::amText () 或 QLocale::pmText (). |
| ap or a | use am/pm display. a/ap will be replaced by a lower-case version of QLocale::amText () 或 QLocale::pmText (). |
| t | the timezone (for example "CEST") |
Any sequence of characters enclosed in single quotes will be included verbatim in the output string (stripped of the quotes), even if it contains formatting characters. Two consecutive single quotes ("''") are replaced by a single quote in the output. All other characters in the format string are included verbatim in the output string.
Formats without separators (e.g. "ddMM") are supported but must be used with care, as the resulting strings aren't always reliably readable (e.g. if "dM" produces "212" it could mean either the 2nd of December or the 21st of February).
格式字符串范例 (假定
QTime
是 14:13:09.042 且系统区域设置为
en_US
)
| 格式 | 结果 |
|---|---|
| hh:mm:ss.zzz | 14:13:09.042 |
| h:m:s ap | 2:13:9 pm |
| H:m:s a | 14:13:9 pm |
若时间无效，返回空字符串。若 format is empty, the default format "hh:mm:ss" is used.
另请参阅 fromString (), QDate::toString (), QDateTime::toString ()，和 QLocale::toString ().
Constructs a null time object. A null time can be a
QTime
(0, 0, 0, 0) (i.e., midnight) object, except that
isNull
() 返回
true
and
isValid
() 返回
false
.
构造时间采用小时 h ，分钟 m ，秒 s 和毫秒 ms .
h 必须在范围 0 到 23， m and s 必须在范围 0 到 59，和 ms 必须在范围 0 到 999。
另请参阅 isValid ().
返回 QTime object containing a time ms milliseconds later than the time of this object (or earlier if ms is negative).
Note that the time will wrap if it passes midnight. See addSecs () 范例。
返回 null 时间若此时间无效。
另请参阅 addSecs (), msecsTo ()，和 QDateTime::addMSecs ().
返回 QTime object containing a time s seconds later than the time of this object (or earlier if s is negative).
注意，时间将卷绕，若过了午夜。
返回 null 时间若此时间无效。
范例：
QTime n(14, 0, 0); // n == 14:00:00 QTime t; t = n.addSecs(70); // t == 14:01:10 t = n.addSecs(-70); // t == 13:58:50 t = n.addSecs(10 * 60 * 60 + 5); // t == 00:00:05 t = n.addSecs(-15 * 60 * 60); // t == 23:00:00
另请参阅 addMSecs (), secsTo ()，和 QDateTime::addSecs ().
[static]
QTime
QTime::
currentTime
()
Returns the current time as reported by the system clock.
Note that the accuracy depends on the accuracy of the underlying operating system; not all systems provide 1-millisecond accuracy.
Furthermore, currentTime() only increases within each day; it shall drop by 24 hours each time midnight passes; and, beside this, changes in it may not correspond to elapsed time, if a daylight-saving transition intervenes.
另请参阅 QDateTime::currentDateTime () 和 QDateTime::currentDateTimeUtc ().
Returns the number of milliseconds that have elapsed since the last time start () 或 restart () 被调用。
Note that the counter wraps to zero 24 hours after the last call to start () or restart.
Note that the accuracy depends on the accuracy of the underlying operating system; not all systems provide 1-millisecond accuracy.
警告： If the system's clock setting has been changed since the last time start () 或 restart () was called, the result is undefined. This can happen when daylight-saving time is turned on or off.
[static]
QTime
QTime::
fromMSecsSinceStartOfDay
(
int
msecs
)
返回新的 QTime instance with the time set to the number of msecs since the start of the day, i.e. since 00:00:00.
若 msecs falls outside the valid range an invalid QTime 将被返回。
另请参阅 msecsSinceStartOfDay ().
[static]
QTime
QTime::
fromString
(const
QString
&
string
,
Qt::DateFormat
format
= Qt::TextDate)
Returns the time represented in the string 作为 QTime 使用 format given, or an invalid time if this is not possible.
Note that fromString() uses a "C" locale encoded string to convert milliseconds to a float value. If the default locale is not "C", this may result in two conversion attempts (if the conversion fails for the default locale). This should be considered an implementation detail.
另请参阅 toString () 和 QLocale::toTime ().
[static]
QTime
QTime::
fromString
(const
QString
&
string
, const
QString
&
format
)
返回 QTime 表示通过 string ，使用 format given, or an invalid time if the string cannot be parsed.
These expressions may be used for the format:
| 表达式 | 输出 |
|---|---|
| h | the hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display) |
| hh | the hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display) |
| m | the minute without a leading zero (0 to 59) |
| mm | the minute with a leading zero (00 to 59) |
| s | the whole second, without any leading zero (0 to 59) |
| ss | the whole second, with a leading zero where applicable (00 to 59) |
| z |
the fractional part of the second, to go after a decimal point, without trailing zeroes (0 to 999). Thus "
s.z
" reports the seconds to full available (millisecond) precision without trailing zeroes.
|
| zzz | the fractional part of the second, to millisecond precision, including trailing zeroes where applicable (000 to 999). |
| AP | interpret as an AM/PM time. AP must be either "AM" or "PM". |
| ap | Interpret as an AM/PM time. ap must be either "am" or "pm". |
All other input characters will be treated as text. Any sequence of characters that are enclosed in single quotes will also be treated as text and not be used as an expression.
QTime time = QTime::fromString("1mm12car00", "m'mm'hcarss"); // time is 12:01.00
If the format is not satisfied, an invalid QTime is returned. Expressions that do not expect leading zeroes to be given (h, m, s and z) are greedy. This means that they will use two digits even if this puts them outside the range of accepted values and leaves too few digits for other sections. For example, the following string could have meant 00:07:10, but the m will grab two digits, resulting in an invalid time:
QTime time = QTime::fromString("00:710", "hh:ms"); // invalid
Any field that is not represented in the format will be set to zero. For example:
QTime time = QTime::fromString("1.30", "m.s"); // time is 00:01:30.000
另请参阅 toString (), QDateTime::fromString (), QDate::fromString ()，和 QLocale::toTime ().
Returns the hour part (0 to 23) of the time.
返回 -1，若时间无效。
另请参阅 minute (), second ()，和 msec ().
返回
true
if the time is null (i.e., the
QTime
object was constructed using the default constructor); otherwise returns false. A null time is also an invalid time.
另请参阅 isValid ().
返回
true
if the time is valid; otherwise returns
false
. For example, the time 23:30:55.746 is valid, but 24:12:30 is invalid.
另请参阅 isNull ().
[static]
bool
QTime::
isValid
(
int
h
,
int
m
,
int
s
,
int
ms
= 0)
这是重载函数。
返回
true
if the specified time is valid; otherwise returns false.
The time is valid if h is in the range 0 to 23, m and s are in the range 0 to 59, and ms is in the range 0 to 999.
范例：
QTime::isValid(21, 10, 30); // returns true QTime::isValid(22, 5, 62); // returns false
Returns the minute part (0 to 59) of the time.
返回 -1，若时间无效。
另请参阅 hour (), second ()，和 msec ().
Returns the millisecond part (0 to 999) of the time.
返回 -1，若时间无效。
另请参阅 hour (), minute ()，和 second ().
Returns the number of msecs since the start of the day, i.e. since 00:00:00.
另请参阅 fromMSecsSinceStartOfDay ().
Returns the number of milliseconds from this time to t 。若 t is earlier than this time, the number of milliseconds returned is negative.
因为 QTime measures time within a day and there are 86400 seconds in a day, the result is always between -86400000 and 86400000 ms.
返回 0 若时间无效。
另请参阅 secsTo (), addMSecs ()，和 QDateTime::msecsTo ().
Sets this time to the current time and returns the number of milliseconds that have elapsed since the last time start () or restart() was called.
This function is guaranteed to be atomic and is thus very handy for repeated measurements. Call start () to start the first measurement, and restart() for each later measurement.
Note that the counter wraps to zero 24 hours after the last call to start () or restart().
警告： If the system's clock setting has been changed since the last time start () or restart() was called, the result is undefined. This can happen when daylight-saving time is turned on or off.
另请参阅 start (), elapsed ()，和 currentTime ().
Returns the second part (0 to 59) of the time.
返回 -1，若时间无效。
另请参阅 hour (), minute ()，和 msec ().
Returns the number of seconds from this time to t 。若 t is earlier than this time, the number of seconds returned is negative.
因为 QTime measures time within a day and there are 86400 seconds in a day, the result is always between -86400 and 86400.
secsTo() does not take into account any milliseconds.
返回 0 若时间无效。
另请参阅 addSecs () 和 QDateTime::secsTo ().
Sets the time to hour h ，分钟 m ，秒 s 和毫秒 ms .
h
必须在范围 0 到 23，
m
and
s
必须在范围 0 到 59，和
ms
must be in the range 0 to 999. Returns
true
if the set time is valid; otherwise returns
false
.
另请参阅 isValid ().
Sets this time to the current time. This is practical for timing:
QTime t; t.start(); some_lengthy_task(); qDebug("Time elapsed: %d ms", t.elapsed());
另请参阅 restart (), elapsed ()，和 currentTime ().
这是重载函数。
以字符串形式返回时间。 format 参数确定字符串的格式。
若 format is Qt::TextDate , the string format is HH:mm:ss; e.g. 1 second before midnight would be "23:59:59".
若 format is Qt::ISODate , the string format corresponds to the ISO 8601 extended specification for representations of dates, represented by HH:mm:ss. To include milliseconds in the ISO 8601 date, use the format Qt::ISODateWithMs , which corresponds to HH:mm:ss.zzz.
若 format is Qt::SystemLocaleShortDate or Qt::SystemLocaleLongDate , the string format depends on the locale settings of the system. Identical to calling QLocale::system (). toString (time, QLocale::ShortFormat ) 或 QLocale::system (). toString (time, QLocale::LongFormat ).
若 format is Qt::DefaultLocaleShortDate or Qt::DefaultLocaleLongDate , the string format depends on the default application locale. This is the locale set with QLocale::setDefault (), or the system locale if no default locale has been set. Identical to calling
QLocale().toString(time, QLocale::ShortFormat) or QLocale().toString(time, QLocale::LongFormat) .
若 format is Qt::RFC2822Date , the string is formatted in an RFC 2822 compatible way. An example of this formatting is "23:59:20".
若时间无效，返回空字符串。
另请参阅 fromString (), QDate::toString (), QDateTime::toString ()，和 QLocale::toString ().
返回
true
if this time is different from
t
；否则返回
false
.
返回
true
若此时间早于
t
；否则返回
false
.
返回
true
若此时间早于或等于
t
；否则返回
false
.
返回
true
若此时间等于
t
；否则返回
false
.
返回
true
若此时间晚于
t
；否则返回
false
.
返回
true
若此时间 >=
t
；否则返回
false
.
写入 time 到流 out .
另请参阅 序列化 Qt 数据类型 .
读取时间从流 in 进给定 time .
另请参阅 序列化 Qt 数据类型 .