QString的不常见用法

QString str("Hello");

QString str = "Hello";

static const QChar data[4] = { 0x0055, 0x006e, 0x10e3, 0x03a3 };
QString str(data, 4);

QString str;
str.resize(4);

str[0] = QChar('U');
str[1] = QChar('n');
str[2] = QChar(0x10e3);
str[3] = QChar(0x03a3);

QString str;
str.sprintf("%s %.3f", "float", 3.1415926);
//str结果是"float 3.14"

QString str;
str.setNum(10); //str = "10"
str.setNum(10, 16); //str = "a"
str.setNum(10.12345); //str = "10.12345"

QString i; // current file's number
QString total; // number of files to process
QString fileName; // current file's name

QString status = QString("Processing file %1 of %2: %3")
.arg(i).arg(total).arg(fileName);

参考：http://blog.csdn.net/xgbing/article/details/7770854

------------------------------------------------------------------

   1)Char * 初始化

  QString str = "Hello";

          QString converts the const char * data into Unicode using the fromAscii() function. 

          2)QChar[]数组初始化

static const QChar data[4] = { 0x0055, 0x006e, 0x10e3, 0x03a3 };
QString str(data, 4);

            也可以这样

QRegExp pattern;
static const QChar unicode[] = { 0x005A, 0x007F, 0x00A4, 0x0060,
0x1009, 0x0020, 0x0020};
int size = sizeof(unicode) / sizeof(QChar);
QString str = QString::fromRawData(unicode, size);

            3)还可以通过risize()函数和每个QChar字符进行初始化

QString str;
str.resize(4);

str[0] = QChar('U');
str[1] = QChar('n');
str[2] = QChar(0x10e3);
str[3] = QChar(0x03a3);

           通过at()函数进行每个字符读取

QString str;

 for (int i = 0; i < str.size(); ++i) {
     if (str.at(i) >= QChar('a') && str.at(i) <= QChar('f'))
         qDebug() << "Found character in range [a-f]";
 }

参考：http://qimo601.iteye.com/blog/1432867