Qt's QTimer usage and skills summary

Introduction

QTimer is a timer class in Qt, used to perform timing operations, such as triggering a slot function or executing specific code after a period of time intervals. It provides flexible timing functions that can be used to handle various time-related tasks. It works based on the Qt-based event loop mechanism.

Main function description

• Constructor:

  • QTimer(QObject *parent = nullptr)

• Timer control function:

  • void start(int msec): Start the timer and set the time interval to msec milliseconds.
  • void stop(): Stop the timer, that is, the timing event will no longer be triggered.

• Timer status function:

  • bool isActive() const: determines whether the timer is active.

• Timer signal and slot function:

  • void timeout(): The signal triggered by the timer can be connected to the slot function to handle timing events.

In addition to the above functions, QTimer also has a singleShot() function, which provides a simple function with only one-time timing.

Usage and usage techniques

• Create a timer object:

  QTimer *timer = new QTimer(parent);

• Set the timer start time and time interval:

  timer->start(1000);  // Every other1Triggers a timer event once in seconds

• Handle events triggered by timer:

  connect(timer, &QTimer::timeout, []() {
      // Timed event processing code});

• Stop timer:

  timer->stop();  // Stop the timer

Example

#include <QApplication>
#include <QDebug>
#include <QTimer>
int main(int argc, char *argv[]) {
    QApplication app(argc, argv);
    QTimer timer;
    (1000);  // Trigger the timer event every 1 second    QObject::connect(&timer, &QTimer::timeout, []() {
        qDebug() << "Timer triggered!";
    });
    return ();
}

explain

The above code uses QTimer to create a timer basic process. The time interval of the timer is set by calling the start function and the timeout signal is connected to the slot function to handle the timing events. The timer is triggered every 1 second, and the slot function will output a debugging information.

in conclusion

QTimer is a class in Qt used to implement timing operations and provides simple and flexible timing functions.
By starting the timer, setting the timer time interval, and connecting the corresponding signal and slot functions, it is possible to trigger a specific operation within a specific time interval.
QTimer is suitable for various scenarios where timing triggering functions are required, such as timed update of UI, timed sending network requests, timed refreshing data, etc.
Simplifies the processing of time-related tasks and provides more convenience for developers.

tips

After applying what you have learned, you will use the QTimer class and the previously released QMainWindow, QDialog, QPushButton, QLabel and other categories to implement a lottery program.

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