A few questoins about Qt

[HelloDan]

1 By default, that's not a minimize button in the Qt widget in windows, but a help ("?" symbol) button. If I want to add a minimize button for a dialog at the same remove the help symbol. What I should do.

2 Why I write a file in the patten in a console window:
QFile file("C:\abc\test.txt");
it doesn,t work. But it work in this way : QFile file("C:\\abc\\test.txt"); At the same time, I get the file name from QFileDialog::getOpenFileName and do not need to replace '\' with "\\". and it work fine. Why?

3 My code fragment is showed as the following:

if(cloudCheckBox->checkState()==Qt::Checked);
  	{
  	  for(size_t i=9;i<17;++i)
  	  {
  	    trimCloud(list[i]);	
  	  } 	
  	}

if(cloudCheckBox->checkState()==Qt::Checked);
  	{
  	  for(size_t i=9;i<17;++i)
  	  {
  	    trimCloud(list[i]);	
  	  } 	
  	}

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It's strange that even I do not click the CheckBox, but it still execute the above code fragment. I try cloudCheckBox->isChecked() instead, I got the same result. Why?

By the way, in the constructor function, I set the CheckBox true.

cloudCheckBox->setChecked(true);
  windSpeedCheckBox->setChecked(true);

cloudCheckBox->setChecked(true);
  windSpeedCheckBox->setChecked(true);

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When i run the app, I click to remove the "√".



4 From my perspective, I do think that try my thinking in a console window is very useful. Also because that I don't know how to test my code in a GUI program, it's very trival.
How do you solve this problem?

Thanks! Any relpy is appreciated!