QListWidgetItem* item = new QListWidgetItem("Item 1"); item->setCheckState(Qt::Checked);
for(int i = 0; i < listWidget->count(); ++i) { QListWidgetItem* item = listWidget->item(i); item->setCheckState(Qt::Checked); }This code snippet checks all items in a QListWidget by iterating through all items and setting their check state to Qt::Checked. Package library: Qt Core library.