**Course Title:** Qt 6 Application Development with C++ **Section Title:** Working with Files and User Input **Topic:** Building an Application that Allows File Selection and Manipulation. (Lab Topic) ### Overview In this lab, we will build a simple Qt application that allows users to select files, display file properties, and manipulate file content. This application will demonstrate how to use Qt's file management classes, such as `QFileDialog` and `QFile`, to interact with the file system. We will also cover error handling and robustness of the application. ### Step 1: Create a New Qt Project Open Qt Creator and create a new project by selecting "File" -> "New File or Project". Choose "Application" under the "Projects" tab and select "Qt Widgets Application". Name your project "FileExplorer". ### Step 2: Design the User Interface In the "FileExplorer" project, open the "mainwindow.ui" file. This is where you will design the user interface for your application. Drag and drop the following widgets from the "Widgetbox" panel: * QLabel (1) - for displaying the selected file path * QPushButton (2) - for opening the file dialog * QTextBrowser (1) - for displaying the selected file content * QTextBrowser (1) - for displaying the file properties (size, modified date, etc.) Arrange these widgets in a QVBoxLayout or use any other layout that suits your needs. ### Step 3: Implement File Dialog and File Properties Display In the "mainwindow.cpp" file, include the necessary headers: ```cpp #include <QFileDialog> #include <QFile> #include <QFileInfo> ``` Create a slot function for the "Open File" button: ```cpp void MainWindow::on_pushButton_clicked() { QString filePath = QFileDialog::getOpenFileName(this, "Open File", QDir::homePath(), "All Files (*.*)"); if (!filePath.isEmpty()) { // Display the selected file path ui->label->setText(filePath); // Get file properties using QFileInfo QFileInfo fileInfo(filePath); QString fileSize = QLatin1String("%1 KB").arg(fileInfo.size() / 1024); QString fileModified = fileInfo.lastModified().toString("yyyy-MM-dd hh:mm:ss"); QString fileProperties = QString("Size: %1\nModified: %2").arg(fileSize).arg(fileModified); // Display file properties ui->textBrowser_2->setText(fileProperties); } } ``` This code opens a file dialog, retrieves the selected file path, and displays the file properties (size, modified date) using `QFileInfo`. ### Step 4: Display File Content Create a slot function to display the selected file content: ```cpp void MainWindow::on_pushButton_2_clicked() { // Get the selected file path QString filePath = ui->label->text(); // Check if the file is empty if (filePath.isEmpty()) { return; } // Read the file content QFile file(filePath); if (file.open(QIODevice::ReadOnly | QIODevice::Text)) { QTextStream stream(&file); ui->textBrowser->setText(stream.readAll()); } else { QMessageBox::critical(this, tr("Error"), tr("Failed to open file")); } } ``` This code reads the selected file content using `QFile` and displays it in the `QTextBrowser`. ### Conclusion In this lab, we built a simple Qt application that allows users to select files, display file properties, and manipulate file content. We covered how to use Qt's file management classes, such as `QFileDialog` and `QFile`, to interact with the file system. **Example Code:** You can find the complete example code for this lab on [Qt GitHub](https://github.com/qt/qtbase/tree/dev/examples/corelib/files). **Troubleshooting:** If you encounter issues with file dialog or file properties display, ensure that you have included all necessary headers and properly connected the slot functions. **What's Next:** In the next topic, we will explore how to integrate SQL databases with Qt using `QSqlDatabase`. **Discussion:** Leave a comment below if you have any questions or need further clarification on any of the concepts covered in this lab. Your feedback is essential in helping us improve the quality of our materials. For the next topic, we will move on to [Introduction to SQL databases in Qt using QSqlDatabase](https://doc.qt.io/qt-6/sql-database.html).