QKeyEvent keyPressEvent不检测方向键?

I have a program that captures a single key press and then outputs the key that is being pressed. The problem is, I am not able to return the value of the key being pressed and cannot get the arrow keys to output anything at all. Here's my code:

我有一个程序，它捕捉一个按键，然后输出被按下的键。问题是，我不能返回键被按的值，不能得到箭头键来输出任何东西。这是我的代码:

myApp.h

myApp.h

class someClass: public QDialog
{
  Q_OBJECT

public:
  ...<snip>...

private:
  ...<snip>...

protected:
  void keyPressEvent(QKeyEvent *e);
};

myApp.cpp

myApp.cpp

MyApp::MyApp(QWidget *parent) :
  QDialog(parent),
  ui(new Ui::myApp)
{
  QWidget::grabKeyboard();
  ui->setupUi(this);
}

void someClass::keyPressEvent(QKeyEvent *e)
{
  qDebug() << "You typed " + e->key();
}

There are two issues here. First, when I type any key, I get output like the following in the Debug pane:

这里有两个问题。首先，当我键入任何键时，我在调试窗格中得到如下输出:

gw492_32\include/QtCore/qstring.h
w492_32\include/QtCore/qstring.h
492_32\include/QtCore/qstring.h
92_32\include/QtCore/qstring.h

I typed abcd to get the above. Shouldn't key() give me the integer value of the key pressed?

我键入abcd以获得上面的内容。键()不应该给我按下键的整数值吗?

The second issue is that when I hit one of the arrow keys, I get nothing in the debug pane except for a blank line. Again, shouldn't I be seeing the integer value for the Up arrow? (values for keys listed here). How would I then output the ASCII value for the key?

第二个问题是，当我点击一个箭头键时，除了一个空行之外，在debug窗格中我什么也得不到。我是不是应该看到向上箭头的整数值?(此处列出的键值)。然后如何输出密钥的ASCII值?

Any help is appreciated.

任何帮助都是感激。

1 个解决方案

#1

The output definitely looks like unwanted pointer arithmetic is happening. And it's undefined behavior.

输出肯定看起来像不需要的指针算法。未定义的行为。

"You typed " + e->key()

advances the pointer to "You typed " by e->key() and makes it point to another location, which is in this case occupied by the string you're getting as output.

通过e->键()将指针移到“您输入”的指针，并使它指向另一个位置，在这个情况下，这个位置被作为输出的字符串占用。

If you want to print it properly, do any of the following:

如果你想正确地打印它，可以做以下任何一件事:

qDebug() << "You typed " << e->key();
qDebug() << "You typed " + QString::number(e->key());
qDebug() << QString("You typed %1").arg(e->key());

#1