QT获取系统时间，以及设置日期格式

蔚落 2022-07-15 12:57 296阅读 0赞

例如我要在一个label上设置当前时间

QDateTime time = QDateTime::currentDateTime();//获取系统现在的时间

QString str = time.toString("yyyy-MM-dd hh:mm:ss ddd"); //设置显示格式

label->setText(str);//在标签上显示时间

[QString][] QDateTime::toString ( const [QString][] & *format* ) const

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

These expressions may be used for the date:

<table style="color:rgb(0,0,0); font-family:Arial; font-size:14px"> 
 <thead> 
  <tr> 
   <th>Expression</th> 
   <th>Output</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>d</td> 
   <td>the day as number without a leading zero (1 to 31)</td> 
  </tr> 
  <tr> 
   <td>dd</td> 
   <td>the day as number with a leading zero (01 to 31)</td> 
  </tr> 
  <tr> 
   <td>ddd</td> 
   <td>the abbreviated localized day name (e.g. 'Mon' to 'Sun'). Uses&nbsp;<a href="http://hi.baidu.com/fc/editor/qdate.html#shortDayName" style="color:rgb(0,79,175); text-decoration:none" rel="nofollow">QDate::shortDayName</a>().</td> 
  </tr> 
  <tr> 
   <td>dddd</td> 
   <td>the long localized day name (e.g. 'Monday' to '<a href="http://hi.baidu.com/fc/editor/qt.html#DayOfWeek-enum" style="color:rgb(0,79,175); text-decoration:none" rel="nofollow">Qt::Sunday</a>'). Uses&nbsp;<a href="http://hi.baidu.com/fc/editor/qdate.html#longDayName" style="color:rgb(0,79,175); text-decoration:none" rel="nofollow">QDate::longDayName</a>().</td> 
  </tr> 
  <tr> 
   <td>M</td> 
   <td>the month as number without a leading zero (1-12)</td> 
  </tr> 
  <tr> 
   <td>MM</td> 
   <td>the month as number with a leading zero (01-12)</td> 
  </tr> 
  <tr> 
   <td>MMM</td> 
   <td>the abbreviated localized month name (e.g. 'Jan' to 'Dec'). Uses&nbsp;<a href="http://hi.baidu.com/fc/editor/qdate.html#shortMonthName" style="color:rgb(0,79,175); text-decoration:none" rel="nofollow">QDate::shortMonthName</a>().</td> 
  </tr> 
  <tr> 
   <td>MMMM</td> 
   <td>the long localized month name (e.g. 'January' to 'December'). Uses&nbsp;<a href="http://hi.baidu.com/fc/editor/qdate.html#longMonthName" style="color:rgb(0,79,175); text-decoration:none" rel="nofollow">QDate::longMonthName</a>().</td> 
  </tr> 
  <tr> 
   <td>yy</td> 
   <td>the year as two digit number (00-99)</td> 
  </tr> 
  <tr> 
   <td>yyyy</td> 
   <td>the year as four digit number</td> 
  </tr> 
 </tbody> 
</table>

These expressions may be used for the time:

<table style="color:rgb(0,0,0); font-family:Arial; font-size:14px"> 
 <thead> 
  <tr> 
   <th>Expression</th> 
   <th>Output</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>h</td> 
   <td>the hour without a leading zero (0 to 23 or 1 to 12 if AM/PM display)</td> 
  </tr> 
  <tr> 
   <td>hh</td> 
   <td>the hour with a leading zero (00 to 23 or 01 to 12 if AM/PM display)</td> 
  </tr> 
  <tr> 
   <td>m</td> 
   <td>the minute without a leading zero (0 to 59)</td> 
  </tr> 
  <tr> 
   <td>mm</td> 
   <td>the minute with a leading zero (00 to 59)</td> 
  </tr> 
  <tr> 
   <td>s</td> 
   <td>the second without a leading zero (0 to 59)</td> 
  </tr> 
  <tr> 
   <td>ss</td> 
   <td>the second with a leading zero (00 to 59)</td> 
  </tr> 
  <tr> 
   <td>z</td> 
   <td>the milliseconds without leading zeroes (0 to 999)</td> 
  </tr> 
  <tr> 
   <td>zzz</td> 
   <td>the milliseconds with leading zeroes (000 to 999)</td> 
  </tr> 
  <tr> 
   <td>AP</td> 
   <td>use AM/PM display.&nbsp;<em>AP</em>&nbsp;will be replaced by either "AM" or "PM".</td> 
  </tr> 
  <tr> 
   <td>ap</td> 
   <td>use am/pm display.&nbsp;<em>ap</em>&nbsp;will be replaced by either "am" or "pm".</td> 
  </tr> 
 </tbody> 
</table>

All other input characters will be ignored. Any sequence of characters that are enclosed in singlequotes will be treated as text and not be used as an expression. Two consecutive singlequotes ("''") are replaced by a singlequote in the output.

Example format strings (assumed that the [QDateTime][] is 21 May 2001 14:13:09):

<table style="color:rgb(0,0,0); font-family:Arial; font-size:14px"> 
 <thead> 
  <tr> 
   <th>Format</th> 
   <th>Result</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>dd.MM.yyyy</td> 
   <td>21.05.2001</td> 
  </tr> 
  <tr> 
   <td>ddd MMMM d yy</td> 
   <td>Tue May 21 01</td> 
  </tr> 
  <tr> 
   <td>hh:mm:ss.zzz</td> 
   <td>14:13:09.042</td> 
  </tr> 
  <tr> 
   <td>h:m:s ap</td> 
   <td>2:13:9 pm</td> 
  </tr> 
 </tbody> 
</table>

[QString]: http://hi.baidu.com/fc/editor/qstring.html
[QDateTime]: http://hi.baidu.com/fc/editor/qdatetime.html