Qt学习笔记0405

#include <QtGui>
#include <QMessageBox>
#include <QApplication>
#include <QInputDialog>

int main (int argc, char* argv[]) {                                          //1
QApplication app(argc, argv);                                            //2
QTextStream cout(stdout);                                                //3

int answer = 0;                                                          //4

do {
int factArg = 0;
int fact(1);
factArg = QInputDialog::getInt(0,
"Factorial Calculator",
"Factorial of:",
1);                                   //5

cout << "User entered: " << factArg << endl;

int i=2;
while (i <= factArg) {
fact = fact * i;
++i;
}

QString response = QString("The factorial of %1 is %2.\n%3")
.arg(factArg).arg(fact)
.arg("Compute another factorial?");                              //6

answer = QMessageBox::question(0,
"Play again?",
response,
QMessageBox::Yes | QMessageBox::No);  //7

} while (answer == QMessageBox::Yes);                                    //8

return EXIT_SUCCESS;
}

/*
1 主函数的开始，并返回int
2 所有GUI应用的开端
3 创建模拟的标准输出cout
4 用于DO循环的判定
5 定义一个整型数据输入对话框（QInputDialog::​getInt）
6 .arg可作为替换符，arg()将替换QString中的 %n (%1 %2 %3 ...%9)
7 信息框其中一种：QMessageBox::question的形式
8 通过位运算来判定循环条件
*/