Qt没有直接的接口去获取到当前系统用户名，只能够间接的通过现有的接口去获取。（比如下边的例子通过获取home路径）

//Qt4 version
QString getUserName() 
{
    QString userName = QDesktopServices::storageLocation(QDesktopServices::HomeLocation);
    userName = userName.section("/", -1, -1); 
    return userName; 
}

  //Qt5 version

QString getUserName()
{
    QString userPath = QStandardPaths::writableLocation(QStandardPaths::HomeLocation); 
    QString userName = userPath.section("/", -1, -1); 
    return userName; 
}