如何处理用户按下 QInputDialog 中的取消按钮？

Question

这是我使用 Qt 的第一周，如果我不太了解基础知识，请原谅我。在下面代码的注释部分，我想编写处理QInputDialog 上的取消按钮的代码。

#include <QtWidgets>

int main (int argc, char* argv[]) {              
  QApplication app(argc, argv);                  
  QTextStream cout(stdout);                       
  int answer;

  do {  
    int celciusArg = 0;
    int farenheit;
    celciusArg = QInputDialog::getInt(0, "Celcius Calculator",
        "Convert this number to Farenheit:", 1);

    // I'd like to say here:
    // if (user clicked cancel)
    //      then (close the widget)

    cout << "User entered: " << celciusArg
         << endl;
    farenheit = celciusArg * 1.8 + 32;

    QString response = QString("%1 degrees celcius is %2 degrees farenheit .\n%3")
        .arg(celciusArg).arg(farenheit)        /* Each %n is replaced with an arg() value. */
        .arg("Convert another temperature?");  /* Long statements can continue on multiple lines, as long as they are broken on token boundaries. */
    answer = QMessageBox::question(0, "Play again?", response,
        QMessageBox::Yes| QMessageBox::No);    /* Bitwise or of two values. */
  } while (answer == QMessageBox::Yes);
  return EXIT_SUCCESS;
}

Answer 1

阅读文档有很大帮助：

如果 ok 不为空，如果用户按下 OK，*ok 将设置为 true，如果用户按下 Cancel，则设置为 false。对话框的父级是父级。该对话框将是模态的并使用小部件标志。

完整原型是：

int QInputDialog::getInt(QWidget * parent, const QString & title, const QString & label, int value = 0, int min = -2147483647, int max = 2147483647, int step = 1, bool * ok = 0, Qt::WindowFlags flags = 0)

所以这里你只需要使用bool * ok:

bool isOkPressed{};
int celciusArg = 0;
int farenheit;
celciusArg = QInputDialog::getInt(0, "Celcius Calculator",
    "Convert this number to Farenheit:", 1, -2147483647, 2147483647, 1, &isOkPressed);

if (isOkPressed) {
    // here you go
}

QInputDialog::getInt() documentation

Answer 2

改成

bool ok;
celciusArg = QInputDialog::getInt(0, "Celcius Calculator",
    "Convert this number to Farenheit:", 0, 0, 100, 1, &ok);

if (ok)
    //pressed ok
else
    //pressed cancel

第一个零是默认值，第二个是最小值，100 应该是最大值，1 是增量/减量，如果你想从 30 C 开始从 -100 C 到 200 C 你必须使用

celciusArg = QInputDialog::getInt(0, "Celcius Calculator",
    "Convert this number to Farenheit:", 30, -100, 200, 1, &ok);