QT Study notes: Qtimer and Qtime

Qtimer Class

Qtimer is a timer class
It's used in three steps, creating objects, connecting signal and slot functions, start ()

    Qtimer *timer = new Qtimer (this);
    Connect (timer, SIGNAL (), this, SLOT (update ()));
    Timer->start (1000);

where SIGNAL (timeout ()) means: Whenever the timer ends, the timer is zeroed and re-timed, and a signal activation slot function is sent.

While Timer->start (1000), 1000 of which is 1000 milliseconds, means that each timeout interval is 1000ms

If we want this timer to be timed only once, you must use the void Setsingleshot (bool singleshot) function.

    Qtimer *timer = new Qtimer (this);
    Connect (timer, SIGNAL (), this, SLOT (update ()));
    Timer->setsetsingleshot (True)
    Timer->start (60000);

This timer will only countdown for 1 minutes and then end.

Of course, we can also change the timekeeping period

void setinterval (int msec)

qtime Class

Qtime provides a time function for the user, and the difference between the Qtimer and the watch is the same as the stopwatch.

Qtime is primarily used for time operations, and he provides a number of functions that allow users to convert and calculate time.

type	name	Description
	Qtime ()	Constructs an object with a time of 0
	Qtime (int h, int m, int s = 0, int ms = 0)	Constructs an object with an initial time
Qtime	Addmsecs (int ms) const	Increases MS milliseconds based on the current time, MS can be negative
Qtime	Addsecs (int s) const	Increase s seconds based on the current time, s can be negative
Int	Hour () const	Returns the number of hours
Int	Minute () const	Returns the number of minutes
Int	Second () const	return seconds
Int	msec () const	return milliseconds
bool	IsValid () const	Determines whether the current object's time is valid, after all, 1 days can not have 25 hours, there will not be 1 minutes 61 seconds
bool	IsValid (int h, int m, int s, int ms = 0)	Determine if the input time is valid
Int	Msecsto (const QTIME & T) const	Calculates the number of milliseconds for the distance time t, or negative if T is earlier than the current time
Int	Secsto (const QTIME & T) const	Calculate the number of seconds from the distance time t
bool	SETHMS (int h, int m, int s, int ms = 0)	Set standard HMS Time, if not compliant, return false
	Here are some of the most important
void	Start ()	Record the current system time as the current time
Int	Restart ()	Logs the current system time as the current time and returns the number of milliseconds between the last call to start () or the restart () function interval
Int	Elapsed () const	Calculates the number of milliseconds between the last Call Start () or the restart () function, equivalent to a timer
QString	ToString (const QString & format) const	Convert time to a specific string format
QString	ToString (Qt::D ateformat format = qt::textdate) const	by QT::D ateformat format Conversion
Qtime	FromString (const QString & string, Qt::D ateformat format = qt::textdate)	Convert from QT::D Ateformat to Qtime object
Qtime	FromString (const QString & string, const QString & format)	Convert from a specific string format to a Qtime object
Qtime	CurrentTime ()	Get the current system time

In addition, the const QString & format needs to be specifically explained in the following table:

Expression	Output
H	The hour without a leading zero (0 to 1 if am/pm display)
hh	The hour with a leading zero (xx to-or-am/pm display)
H	The hour without a leading zero (0 to + even with AM/PM display)
HH	The hour with a leading zero (at even with am/pm display)
M	The minute without a leading zero (0 to 59)
Mm	The minute with a leading zero (xx to 59)
S	The second without a leading zero (0 to 59)
Ss	The second with a leading zero (xx to 59)
Z	The milliseconds without leading zeroes (0 to 999)
zzz	The milliseconds with leading zeroes (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".
T	The timezone (for example "CEST")

Example:

Format	Result
Hh:mm:ss.zzz	14:13:09.042
H:m:s AP	2:13:9 pm
H:m:s A	14:13:9 pm

and Qt::D Ateformat is divided into many kinds, such as qt::textdate, qt::isodate and so on, please see the official note, here is not pointed out.