QDataStream Class Reference |
Constant | Value | Description |
---|---|---|
QDataStream::BigEndian | QSysInfo::BigEndian | Most significant byte first (the default) |
QDataStream::LittleEndian | QSysInfo::LittleEndian | Less significant byte first |
This enum describes the current status of the data stream.
Constant | Value | Description |
---|---|---|
QDataStream::Ok | 0 | The data stream is operating normally. |
QDataStream::ReadPastEnd | 1 | The data stream has read past the end of the data in the underlying device. |
QDataStream::ReadCorruptData | 2 | The data stream has read corrupt data. |
This enum provides symbolic synonyms for the data serialization format version numbers.
Constant | Value | Description |
---|---|---|
QDataStream::Qt_1_0 | 1 | Version 1 (Qt 1.x) |
QDataStream::Qt_2_0 | 2 | Version 2 (Qt 2.0) |
QDataStream::Qt_2_1 | 3 | Version 3 (Qt 2.1, 2.2, 2.3) |
QDataStream::Qt_3_0 | 4 | Version 4 (Qt 3.0) |
QDataStream::Qt_3_1 | 5 | Version 5 (Qt 3.1, 3.2) |
QDataStream::Qt_3_3 | 6 | Version 6 (Qt 3.3) |
QDataStream::Qt_4_0 | 7 | Version 7 (Qt 4.0, Qt 4.1) |
QDataStream::Qt_4_1 | Qt_4_0 | Version 7 (Qt 4.0, Qt 4.1) |
QDataStream::Qt_4_2 | 8 | Version 8 (Qt 4.2) |
QDataStream::Qt_4_3 | 9 | Version 9 (Qt 4.3) |
See also setVersion() and version().
Constructs a data stream that has no I/O device.
See also setDevice().
Constructs a data stream that uses the I/O device d.
Warning: If you use QSocket or QSocketDevice as the I/O device d for reading data, you must make sure that enough data is available on the socket for the operation to successfully proceed; QDataStream does not have any means to handle or recover from short-reads.
See also setDevice() and device().
Constructs a data stream that operates on a byte array, a. The mode describes how the device is to be used.
Alternatively, you can use QDataStream(const QByteArray &) if you just want to read from a byte array.
Since QByteArray is not a QIODevice subclass, internally a QBuffer is created to wrap the byte array.
Constructs a read-only data stream that operates on byte array a. Use QDataStream(QByteArray*, int) if you want to write to a byte array.
Since QByteArray is not a QIODevice subclass, internally a QBuffer is created to wrap the byte array.
Destroys the data stream.
The destructor will not affect the current I/O device, unless it is an internal I/O device (e.g. a QBuffer) processing a QByteArray passed in the constructor, in which case the internal I/O device is destroyed.
Returns true if the I/O device has reached the end position (end of the stream or file) or if there is no I/O device set; otherwise returns false.
See also QIODevice::atEnd().
Returns the current byte order setting -- either BigEndian or LittleEndian.
See also setByteOrder().
Returns the I/O device currently set.
See also setDevice() and unsetDevice().
Reads the buffer s from the stream and returns a reference to the stream.
The buffer s is allocated using new. Destroy it with the delete[] operator.
The l parameter is set to the length of the buffer. If the string read is empty, l is set to 0 and s is set to a null pointer.
The serialization format is a quint32 length specifier first, then l bytes of data.
See also readRawData() and writeBytes().
Reads at most len bytes from the stream into s and returns the number of bytes read. If an error occurs, this function returns -1.
The buffer s must be preallocated. The data is not encoded.
See also readBytes(), QIODevice::read(), and writeRawData().
Resets the status of the data stream.
See also Status, status(), and setStatus().
Sets the serialization byte order to bo.
The bo parameter can be QDataStream::BigEndian or QDataStream::LittleEndian.
The default setting is big endian. We recommend leaving this setting unless you have special requirements.
See also byteOrder().
void QDataStream::setDevice(QIODevice *d)
Sets the I/O device to d.
See also device() and unsetDevice().
Sets the status of the data stream to the status given.
See also Status, status(), and resetStatus().
Sets the version number of the data serialization format to v.
You don't have to set a version if you are using the current version of Qt, but for your own custom binary formats we recommend that you do; see Versioning in the Detailed Description.
In order to accommodate new functionality, the datastream serialization format of some Qt classes has changed in some versions of Qt. If you want to read data that was created by an earlier version of Qt, or write data that can be read by a program that was compiled with an earlier version of Qt, use this function to modify the serialization format used by QDataStream.
Qt Version | QDataStream Version |
---|---|
Qt 4.2 | 8 |
Qt 4.0 | 7 |
Qt 3.3 | 6 |
Qt 3.1, 3.2 | 5 |
Qt 3.0 | 4 |
Qt 2.1, 2.2, 2.3 | 3 |
Qt 2.0 | 2 |
Qt 1.x | 1 |
The Version enum provides symbolic constants for the different versions of Qt. For example:
QDataStream out(file); out.setVersion(QDataStream::Qt_4_0);
See also version() and Version.
Skips len bytes from the device. Returns the number of bytes actually skipped, or -1 on error.
This is equivalent to calling readRawData() on a buffer of length len and ignoring the buffer.
This function was introduced in Qt 4.1.
See also QIODevice::seek().
Returns the status of the data stream.
See also Status, setStatus(), and resetStatus().
Unsets the I/O device. This is the same as calling setDevice(0).
See also device() and setDevice().
Returns the version number of the data serialization format.
See also setVersion() and Version.
Writes the length specifier len and the buffer s to the stream and returns a reference to the stream.
The len is serialized as a quint32, followed by len bytes from s. Note that the data is not encoded.
See also writeRawData() and readBytes().
Writes len bytes from s to the stream. Returns the number of bytes actually written, or -1 on error. The data is not encoded.
See also writeBytes(), QIODevice::write(), and readRawData().
Writes a signed byte, i, to the stream and returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Writes a boolean value, i, to the stream. Returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Writes an unsigned byte, i, to the stream and returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Writes an unsigned 16-bit integer, i, to the stream and returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Writes a signed 16-bit integer, i, to the stream and returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Writes a signed 32-bit integer, i, to the stream and returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Writes an unsigned 64-bit integer, i, to the stream and returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Writes a signed 64-bit integer, i, to the stream and returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Writes an unsigned integer, i, to the stream as a 32-bit unsigned integer (quint32). Returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Writes a 32-bit floating point number, f, to the stream using the standard IEEE 754 format. Returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Writes a 64-bit floating point number, f, to the stream using the standard IEEE 754 format. Returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Writes the '\0'-terminated string s to the stream and returns a reference to the stream.
The string is serialized using writeBytes().
Reads a signed byte from the stream into i, and returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Reads a boolean value from the stream into i. Returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Reads an unsigned byte from the stream into i, and returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Reads an unsigned 16-bit integer from the stream into i, and returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Reads a signed 16-bit integer from the stream into i, and returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Reads an unsigned 32-bit integer from the stream into i, and returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Reads a signed 32-bit integer from the stream into i, and returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Reads an unsigned 64-bit integer from the stream, into i, and returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Reads a signed 64-bit integer from the stream into i, and returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Reads a 32-bit floating point number from the stream into f, using the standard IEEE 754 format. Returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Reads a 64-bit floating point number from the stream into f, using the standard IEEE 754 format. Returns a reference to the stream.
This is an overloaded member function, provided for convenience.
Reads the '\0'-terminated string s from the stream and returns a reference to the stream.
Space for the string is allocated using new -- the caller must destroy it with delete[].
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