Qt入门-文件读写

二进制文件的读写文件可以使用QFile类、QStream

文本文件的读写建议使用QTextStream类，它操作文件更加方便。

打开文件时，需要参数指定打开文件的模式：

Constant		Value	Description
QIODevice::NotOpen	0x0000	The device is not open.
QIODevice::ReadOnly	0x0001	The device is open for reading.
QIODevice::WriteOnly	0x0002	The device is open for writing.
QIODevice::ReadWrite	ReadOnly | WriteOnly	The device is open for reading and writing.
QIODevice::Append	0x0004	The device is opened in append mode, so that all data is written to the end of the file.
QIODevice::Truncate	0x0008	If possible, the device is truncated before it is opened. All earlier contents of the device are lost.
QIODevice::Text	0x0010	When reading, the end-of-line terminators are translated to '\n'. When writing, the end-of-line terminators are translated to the local encoding, for example '\r\n' for Win32.
QIODevice::Unbuffered	0x0020	Any buffer in the device is bypassed.

QIODevice::Text在读写文本文件时使用，这样可以自动转化换行符为本地换行符。

(1)写入文本文件

	QFile f("c:\\test.txt");
	if(!f.open(QIODevice::WriteOnly | QIODevice::Text))
	{
		cout << "Open failed." << endl;
		return -1;
	}

	QTextStream txtOutput(&f);
	QString s1("123");
	quint32 n1(123);

	txtOutput << s1 << endl;
	txtOutput << n1 << endl;

	f.close();

写入的文件内容为：

123

123

(2)读取文本文件

	QFile f("c:\\test.txt");
	if(!f.open(QIODevice::ReadOnly | QIODevice::Text))
	{
		cout << "Open failed." << endl;
		return -1;
	}

	QTextStream txtInput(&f);
	QString lineStr;
	while(!txtInput.atEnd())
	{
		lineStr = txtInput.readLine();
		cout << lineStr << endl;
	}

	f.close();

屏蔽打印的内容为：

123

123