#include <qdatastream.h>
Collaboration diagram for QDataStream:
A data stream is a binary stream of encoded information which is 100% independent of the host computer's operating system, CPU or byte order. For example, a data stream that is written by a PC under Windows can be read by a Sun SPARC running Solaris.
You can also use a data stream to read/write {raw}{raw unencoded binary data}. If you want a "parsing" input stream, see QTextStream.
The QDataStream class implements the serialization of C++'s basic data types, like char, short, int, {char *}, etc. Serialization of more complex data is accomplished by breaking up the data into primitive units.
A data stream cooperates closely with a QIODevice. A QIODevice represents an input/output medium one can read data from and write data to. The QFile class is an example of an I/O device.
Example (write binary data to a stream):
QFile file("file.dat"); file.open(QIODevice::WriteOnly); QDataStream out(&file); // we will serialize the data into the file out << "the answer is"; // serialize a string out << (qint32)42; // serialize an integer
Example (read binary data from a stream):
QFile file("file.dat"); file.open(QIODevice::ReadOnly); QDataStream in(&file); // read the data serialized from the file QString str; qint32 a; in >> str >> a; // extract "the answer is" and 42
Each item written to the stream is written in a predefined binary format that varies depending on the item's type. Supported Qt types include QBrush, QColor, QDateTime, QFont, QPixmap, QString, QVariant and many others. For the complete list of all Qt types supporting data streaming see the {Format of the QDataStream operators}.
For integers it is best to always cast to a Qt integer type for writing, and to read back into the same Qt integer type. This ensures that you get integers of the size you want and insulates you from compiler and platform differences.
To take one example, a {char *} string is written as a 32-bit integer equal to the length of the string including the '\0' byte, followed by all the characters of the string including the '\0' byte. When reading a {char *} string, 4 bytes are read to create the 32-bit length value, then that many characters for the {char *} string including the '\0' terminator are read.
The initial I/O device is usually set in the constructor, but can be changed with setDevice(). If you've reached the end of the data (or if there is no I/O device set) atEnd() will return true.
QDataStream's binary format has evolved since Qt 1.0, and is likely to continue evolving to reflect changes done in Qt. When inputting or outputting complex types, it's very important to make sure that the same version of the stream (version()) is used for reading and writing. If you need both forward and backward compatibility, you can hardcode the version number in the application: @code stream.setVersion(QDataStream::Qt_4_0); \endcode If you are producing a new binary data format, such as a file format for documents created by your application, you could use a QDataStream to write the data in a portable format. Typically, you would write a brief header containing a magic string and a version number to give yourself room for future expansion. For example: @code QFile file("file.xxx"); file.open(QIODevice::WriteOnly); QDataStream out(&file); // Write a header with a "magic number" and a version out << (quint32)0xA0B0C0D0; out << (qint32)123; out.setVersion(QDataStream::Qt_4_0); // Write the data out << lots_of_interesting_data; \endcode Then read it in with: @code QFile file("file.xxx"); file.open(QIODevice::ReadOnly); QDataStream in(&file); // Read and check the header quint32 magic; in >> magic; if (magic != 0xA0B0C0D0) return XXX_BAD_FILE_FORMAT; // Read the version qint32 version; in >> version; if (version < 100) return XXX_BAD_FILE_TOO_OLD; if (version > 123) return XXX_BAD_FILE_TOO_NEW; if (version <= 110) in.setVersion(QDataStream::Qt_3_2); else in.setVersion(QDataStream::Qt_4_0); // Read the data in >> lots_of_interesting_data; if (version >= 120) in >> data_new_in_XXX_version_1_2; in >> other_interesting_data; \endcode You can select which byte order to use when serializing data. The default setting is big endian (MSB first). Changing it to little endian breaks the portability (unless the reader also changes to little endian). We recommend keeping this setting unless you have special requirements. \target raw @section Reading and writing raw binary data You may wish to read/write your own raw binary data to/from the data stream directly. Data may be read from the stream into a preallocated \c{char *} using readRawData(). Similarly data can be written to the stream using writeRawData(). Note that any encoding/decoding of the data must be done by you. A similar pair of functions is readBytes() and writeBytes(). These differ from their \e raw counterparts as follows: readBytes() reads a quint32 which is taken to be the length of the data to be read, then that number of bytes is read into the preallocated \c{char *}; writeBytes() writes a quint32 containing the length of the data, followed by the data. Note that any encoding/decoding of the data (apart from the length quint32) must be done by you. \sa QTextStream QVariant Definition at line 51 of file qdatastream.h.
| enum QDataStream::Version |
This enum provides symbolic synonyms for the data serialization format version numbers.
Qt_1_0 Version 1 (Qt 1.x) Qt_2_0 Version 2 (Qt 2.0) Qt_2_1 Version 3 (Qt 2.1, 2.2, 2.3) Qt_3_0 Version 4 (Qt 3.0) Qt_3_1 Version 5 (Qt 3.1, 3.2) Qt_3_3 Version 6 (Qt 3.3) Qt_4_0 Version 7 (Qt 4.0, Qt 4.1) Qt_4_1 Version 7 (Qt 4.0, Qt 4.1) Qt_4_2 Version 8 (Qt 4.2)
Definition at line 54 of file qdatastream.h.
00054 { 00055 Qt_1_0 = 1, 00056 Qt_2_0 = 2, 00057 Qt_2_1 = 3, 00058 Qt_3_0 = 4, 00059 Qt_3_1 = 5, 00060 Qt_3_3 = 6, 00061 Qt_4_0 = 7, 00062 Qt_4_1 = Qt_4_0, 00063 Qt_4_2 = 8 00064 #if QT_VERSION >= 0x040300 00065 #error Add Qt_4_3 = Qt_4_2 00066 #endif 00067 };
The byte order used for reading/writing the data.
BigEndian Most significant byte first (the default) LittleEndian Less significant byte first
Definition at line 69 of file qdatastream.h.
00069 { 00070 BigEndian = QSysInfo::BigEndian, 00071 LittleEndian = QSysInfo::LittleEndian 00072 };
| enum QDataStream::Status |
This enum describes the current status of the data stream.
Ok The data stream is operating normally. ReadPastEnd The data stream has read past the end of the data in the underlying device. ReadCorruptData The data stream has read corrupt data.
Definition at line 74 of file qdatastream.h.
00074 { 00075 Ok, 00076 ReadPastEnd, 00077 ReadCorruptData 00078 };
| QDataStream::QDataStream | ( | ) |
Constructs a data stream that has no I/O device.
Definition at line 246 of file qdatastream.cpp.
References BigEndian, byteorder, DefaultStreamVersion, dev, noswap, Ok, owndev, q_status, and ver.
00247 { 00248 dev = 0; 00249 owndev = false; 00250 byteorder = BigEndian; 00251 ver = DefaultStreamVersion; 00252 noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian; 00253 q_status = Ok; 00254 }
| QDataStream::QDataStream | ( | QIODevice * | d | ) | [explicit] |
Constructs a data stream that uses the I/O device d.
Definition at line 268 of file qdatastream.cpp.
References BigEndian, byteorder, d, DefaultStreamVersion, dev, noswap, Ok, owndev, q_status, and ver.
00269 { 00270 dev = d; // set device 00271 owndev = false; 00272 byteorder = BigEndian; // default byte order 00273 ver = DefaultStreamVersion; 00274 noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian; 00275 q_status = Ok; 00276 }
| QDataStream::QDataStream | ( | QByteArray * | a, | |
| QIODevice::OpenMode | mode | |||
| ) |
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.
Definition at line 313 of file qdatastream.cpp.
References a, BigEndian, buf, byteorder, DefaultStreamVersion, dev, noswap, Ok, owndev, q_status, and ver.
00314 { 00315 QBuffer *buf = new QBuffer(a); 00316 buf->open(flags); 00317 dev = buf; 00318 owndev = true; 00319 byteorder = BigEndian; 00320 ver = DefaultStreamVersion; 00321 noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian; 00322 q_status = Ok; 00323 }
| QDataStream::QDataStream | ( | const QByteArray & | a | ) |
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.
Definition at line 333 of file qdatastream.cpp.
References a, BigEndian, buf, byteorder, DefaultStreamVersion, dev, noswap, Ok, owndev, q_status, QIODevice::ReadOnly, and ver.
00334 { 00335 QBuffer *buf = new QBuffer; 00336 buf->setData(a); 00337 buf->open(QIODevice::ReadOnly); 00338 dev = buf; 00339 owndev = true; 00340 byteorder = BigEndian; 00341 ver = DefaultStreamVersion; 00342 noswap = QSysInfo::ByteOrder == QSysInfo::BigEndian; 00343 q_status = Ok; 00344 }
| QDataStream::~QDataStream | ( | ) | [virtual] |
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.
Definition at line 355 of file qdatastream.cpp.
| QIODevice * QDataStream::device | ( | ) | const [inline] |
Returns the I/O device currently set.
Definition at line 170 of file qdatastream.h.
Referenced by Server::sendFortune(), and Translator::squeeze().
00171 { return dev; }
| void QDataStream::setDevice | ( | QIODevice * | d | ) |
void QDataStream::setDevice(QIODevice *d)
Sets the I/O device to d.
Definition at line 378 of file qdatastream.cpp.
References d, dev, and owndev.
Referenced by HelpDialog::loadIndexFile(), and unsetDevice().
| void QDataStream::unsetDevice | ( | ) |
Unsets the I/O device. This is the same as calling setDevice(0).
Definition at line 393 of file qdatastream.cpp.
References setDevice().
00394 { 00395 setDevice(0); 00396 }
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| bool QDataStream::atEnd | ( | ) | const |
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.
Definition at line 409 of file qdatastream.cpp.
References QIODevice::atEnd(), and dev.
Referenced by HelpDialog::getAllContents(), and operator>>().
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| QDataStream::Status QDataStream::status | ( | ) | const |
Returns the status of the data stream.
Definition at line 420 of file qdatastream.cpp.
References q_status.
Referenced by operator>>().
00421 { 00422 return q_status; 00423 }
| void QDataStream::setStatus | ( | Status | status | ) |
Sets the status of the data stream to the status given.
Definition at line 440 of file qdatastream.cpp.
Referenced by QHostAddress::operator>>(), QByteArray::operator>>(), operator>>(), operator>>(), and readBytes().
| void QDataStream::resetStatus | ( | ) |
Resets the status of the data stream.
Definition at line 430 of file qdatastream.cpp.
Referenced by operator>>().
| QDataStream::ByteOrder QDataStream::byteOrder | ( | ) | const [inline] |
Returns the current byte order setting -- either BigEndian or LittleEndian.
Definition at line 173 of file qdatastream.h.
References byteorder.
Referenced by operator<<(), and operator>>().
00174 { return byteorder; }
| void QDataStream::setByteOrder | ( | ByteOrder | bo | ) |
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.
Definition at line 472 of file qdatastream.cpp.
References BigEndian, byteorder, LittleEndian, and noswap.
00473 { 00474 byteorder = bo; 00475 if (QSysInfo::ByteOrder == QSysInfo::BigEndian) 00476 noswap = (byteorder == BigEndian); 00477 else 00478 noswap = (byteorder == LittleEndian); 00479 }
| int QDataStream::version | ( | ) | const [inline] |
Returns the version number of the data serialization format.
Definition at line 176 of file qdatastream.h.
References ver.
Referenced by QByteArray::operator<<(), operator<<(), operator<<(), operator>>(), operator>>(), and QTreeWidgetItem::read().
00177 { return ver; }
| void QDataStream::setVersion | ( | int | v | ) | [inline] |
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);
Definition at line 179 of file qdatastream.h.
References ver.
Referenced by Client::readFortune(), FortuneThread::run(), and Server::sendFortune().
00180 { ver = v; }
| QDataStream & QDataStream::operator>> | ( | qint8 & | i | ) |
Reads a signed byte from the stream into i, and returns a reference to the stream.
Definition at line 584 of file qdatastream.cpp.
References c, CHECK_STREAM_PRECOND, dev, QIODevice::getChar(), ReadPastEnd, and setStatus().
00585 { 00586 i = 0; 00587 CHECK_STREAM_PRECOND(*this) 00588 char c; 00589 if (!dev->getChar(&c)) 00590 setStatus(ReadPastEnd); 00591 else 00592 i = qint8(c); 00593 return *this; 00594 }
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| QDataStream & QDataStream::operator>> | ( | quint8 & | i | ) | [inline] |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Reads an unsigned byte from the stream into i, and returns a reference to the stream.
Definition at line 182 of file qdatastream.h.
00183 { return *this >> reinterpret_cast<qint8&>(i); }
| QDataStream & QDataStream::operator>> | ( | qint16 & | i | ) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Reads a signed 16-bit integer from the stream into i, and returns a reference to the stream.
Definition at line 612 of file qdatastream.cpp.
References b, CHECK_STREAM_PRECOND, dev, noswap, p, QIODevice::read(), ReadPastEnd, and setStatus().
00613 { 00614 i = 0; 00615 CHECK_STREAM_PRECOND(*this) 00616 if (noswap) { 00617 if (dev->read((char *)&i, 2) != 2) { 00618 i = 0; 00619 setStatus(ReadPastEnd); 00620 } 00621 } else { 00622 register uchar *p = (uchar *)(&i); 00623 char b[2]; 00624 if (dev->read(b, 2) == 2) { 00625 *p++ = b[1]; 00626 *p = b[0]; 00627 } else { 00628 setStatus(ReadPastEnd); 00629 } 00630 } 00631 return *this; 00632 }
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| QDataStream & QDataStream::operator>> | ( | quint16 & | i | ) | [inline] |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Reads an unsigned 16-bit integer from the stream into i, and returns a reference to the stream.
Definition at line 185 of file qdatastream.h.
00186 { return *this >> reinterpret_cast<qint16&>(i); }
| QDataStream & QDataStream::operator>> | ( | qint32 & | i | ) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Reads a signed 32-bit integer from the stream into i, and returns a reference to the stream.
Definition at line 650 of file qdatastream.cpp.
References b, CHECK_STREAM_PRECOND, dev, noswap, p, QIODevice::read(), ReadPastEnd, and setStatus().
00651 { 00652 i = 0; 00653 CHECK_STREAM_PRECOND(*this) 00654 if (noswap) { 00655 if (dev->read((char *)&i, 4) != 4) { 00656 i = 0; 00657 setStatus(ReadPastEnd); 00658 } 00659 } else { // swap bytes 00660 uchar *p = (uchar *)(&i); 00661 char b[4]; 00662 if (dev->read(b, 4) == 4) { 00663 *p++ = b[3]; 00664 *p++ = b[2]; 00665 *p++ = b[1]; 00666 *p = b[0]; 00667 } else { 00668 setStatus(ReadPastEnd); 00669 } 00670 } 00671 return *this; 00672 }
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| QDataStream & QDataStream::operator>> | ( | quint32 & | i | ) | [inline] |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Reads an unsigned 32-bit integer from the stream into i, and returns a reference to the stream.
Definition at line 188 of file qdatastream.h.
00189 { return *this >> reinterpret_cast<qint32&>(i); }
| QDataStream & QDataStream::operator>> | ( | qint64 & | i | ) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Reads a signed 64-bit integer from the stream into i, and returns a reference to the stream.
Definition at line 689 of file qdatastream.cpp.
References b, CHECK_STREAM_PRECOND, dev, noswap, p, QIODevice::read(), ReadPastEnd, setStatus(), and version().
00690 { 00691 i = qint64(0); 00692 CHECK_STREAM_PRECOND(*this) 00693 if (version() < 6) { 00694 quint32 i1, i2; 00695 *this >> i2 >> i1; 00696 i = ((quint64)i1 << 32) + i2; 00697 } else if (noswap) { // no conversion needed 00698 if (dev->read((char *)&i, 8) != 8) { 00699 i = qint64(0); 00700 setStatus(ReadPastEnd); 00701 } 00702 } else { // swap bytes 00703 uchar *p = (uchar *)(&i); 00704 char b[8]; 00705 if (dev->read(b, 8) == 8) { 00706 *p++ = b[7]; 00707 *p++ = b[6]; 00708 *p++ = b[5]; 00709 *p++ = b[4]; 00710 *p++ = b[3]; 00711 *p++ = b[2]; 00712 *p++ = b[1]; 00713 *p = b[0]; 00714 } else { 00715 setStatus(ReadPastEnd); 00716 } 00717 } 00718 return *this; 00719 }
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| QDataStream & QDataStream::operator>> | ( | quint64 & | i | ) | [inline] |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Reads an unsigned 64-bit integer from the stream, into i, and returns a reference to the stream.
Definition at line 191 of file qdatastream.h.
00192 { return *this >> reinterpret_cast<qint64&>(i); }
| QDataStream & QDataStream::operator>> | ( | bool & | i | ) |
Reads a boolean value from the stream into i. Returns a reference to the stream.
Definition at line 725 of file qdatastream.cpp.
| QDataStream & QDataStream::operator>> | ( | float & | f | ) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Reads a 32-bit floating point number from the stream into f, using the standard IEEE 754 format. Returns a reference to the stream.
Definition at line 741 of file qdatastream.cpp.
References b, CHECK_STREAM_PRECOND, dev, noswap, p, QIODevice::read(), ReadPastEnd, and setStatus().
00742 { 00743 f = 0.0f; 00744 CHECK_STREAM_PRECOND(*this) 00745 if (noswap) { 00746 if (dev->read((char *)&f, 4) != 4) { 00747 f = 0.0f; 00748 setStatus(ReadPastEnd); 00749 } 00750 } else { // swap bytes 00751 uchar *p = (uchar *)(&f); 00752 char b[4]; 00753 if (dev->read(b, 4) == 4) { 00754 *p++ = b[3]; 00755 *p++ = b[2]; 00756 *p++ = b[1]; 00757 *p = b[0]; 00758 } else { 00759 setStatus(ReadPastEnd); 00760 } 00761 } 00762 return *this; 00763 }
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| QDataStream & QDataStream::operator>> | ( | double & | f | ) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Reads a 64-bit floating point number from the stream into f, using the standard IEEE 754 format. Returns a reference to the stream.
Definition at line 774 of file qdatastream.cpp.
References b, CHECK_STREAM_PRECOND, dev, noswap, p, QIODevice::read(), ReadPastEnd, and setStatus().
00775 { 00776 f = 0.0; 00777 CHECK_STREAM_PRECOND(*this) 00778 if (noswap) { 00779 if (dev->read((char *)&f, 8) != 8) { 00780 f = 0.0; 00781 setStatus(ReadPastEnd); 00782 } 00783 } else { // swap bytes 00784 register uchar *p = (uchar *)(&f); 00785 char b[8]; 00786 if (dev->read(b, 8) == 8) { 00787 *p++ = b[7]; 00788 *p++ = b[6]; 00789 *p++ = b[5]; 00790 *p++ = b[4]; 00791 *p++ = b[3]; 00792 *p++ = b[2]; 00793 *p++ = b[1]; 00794 *p = b[0]; 00795 } else { 00796 setStatus(ReadPastEnd); 00797 } 00798 } 00799 return *this; 00800 }
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| QDataStream & QDataStream::operator>> | ( | char *& | s | ) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Reads the ''-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[]}.
Definition at line 813 of file qdatastream.cpp.
References len, and readBytes().
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| QDataStream & QDataStream::operator<< | ( | qint8 | i | ) |
Writes a signed byte, i, to the stream and returns a reference to the stream.
Definition at line 909 of file qdatastream.cpp.
References CHECK_STREAM_PRECOND, dev, and QIODevice::putChar().
00910 { 00911 CHECK_STREAM_PRECOND(*this) 00912 dev->putChar(i); 00913 return *this; 00914 }
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| QDataStream & QDataStream::operator<< | ( | quint8 | i | ) | [inline] |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Writes an unsigned byte, i, to the stream and returns a reference to the stream.
Definition at line 194 of file qdatastream.h.
| QDataStream & QDataStream::operator<< | ( | qint16 | i | ) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Writes a signed 16-bit integer, i, to the stream and returns a reference to the stream.
Definition at line 932 of file qdatastream.cpp.
References b, CHECK_STREAM_PRECOND, dev, noswap, p, and QIODevice::write().
00933 { 00934 CHECK_STREAM_PRECOND(*this) 00935 if (noswap) { 00936 dev->write((char *)&i, sizeof(qint16)); 00937 } else { // swap bytes 00938 register uchar *p = (uchar *)(&i); 00939 char b[2]; 00940 b[1] = *p++; 00941 b[0] = *p; 00942 dev->write(b, 2); 00943 } 00944 return *this; 00945 }
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| QDataStream & QDataStream::operator<< | ( | quint16 | i | ) | [inline] |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Writes an unsigned 16-bit integer, i, to the stream and returns a reference to the stream.
Definition at line 197 of file qdatastream.h.
| QDataStream & QDataStream::operator<< | ( | qint32 | i | ) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Writes a signed 32-bit integer, i, to the stream and returns a reference to the stream.
Definition at line 954 of file qdatastream.cpp.
References b, CHECK_STREAM_PRECOND, dev, noswap, p, and QIODevice::write().
00955 { 00956 CHECK_STREAM_PRECOND(*this) 00957 if (noswap) { 00958 dev->write((char *)&i, sizeof(qint32)); 00959 } else { // swap bytes 00960 register uchar *p = (uchar *)(&i); 00961 char b[4]; 00962 b[3] = *p++; 00963 b[2] = *p++; 00964 b[1] = *p++; 00965 b[0] = *p; 00966 dev->write(b, 4); 00967 } 00968 return *this; 00969 }
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| QDataStream & QDataStream::operator<< | ( | quint32 | i | ) | [inline] |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Writes an unsigned integer, i, to the stream as a 32-bit unsigned integer (quint32). Returns a reference to the stream.
Definition at line 200 of file qdatastream.h.
| QDataStream & QDataStream::operator<< | ( | qint64 | i | ) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Writes a signed 64-bit integer, i, to the stream and returns a reference to the stream.
Definition at line 986 of file qdatastream.cpp.
References b, CHECK_STREAM_PRECOND, dev, noswap, p, version(), and QIODevice::write().
00987 { 00988 CHECK_STREAM_PRECOND(*this) 00989 if (version() < 6) { 00990 quint32 i1 = i & 0xffffffff; 00991 quint32 i2 = i >> 32; 00992 *this << i2 << i1; 00993 } else if (noswap) { // no conversion needed 00994 dev->write((char *)&i, sizeof(qint64)); 00995 } else { // swap bytes 00996 register uchar *p = (uchar *)(&i); 00997 char b[8]; 00998 b[7] = *p++; 00999 b[6] = *p++; 01000 b[5] = *p++; 01001 b[4] = *p++; 01002 b[3] = *p++; 01003 b[2] = *p++; 01004 b[1] = *p++; 01005 b[0] = *p; 01006 dev->write(b, 8); 01007 } 01008 return *this; 01009 }
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| QDataStream & QDataStream::operator<< | ( | quint64 | i | ) | [inline] |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Writes an unsigned 64-bit integer, i, to the stream and returns a reference to the stream.
Definition at line 203 of file qdatastream.h.
| QDataStream & QDataStream::operator<< | ( | bool | i | ) |
Writes a boolean value, i, to the stream. Returns a reference to the stream.
Definition at line 1024 of file qdatastream.cpp.
References CHECK_STREAM_PRECOND, dev, and QIODevice::putChar().
01025 { 01026 CHECK_STREAM_PRECOND(*this) 01027 dev->putChar(qint8(i)); 01028 return *this; 01029 }
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| QDataStream & QDataStream::operator<< | ( | float | f | ) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Writes a 32-bit floating point number, f, to the stream using the standard IEEE 754 format. Returns a reference to the stream.
Definition at line 1038 of file qdatastream.cpp.
References b, CHECK_STREAM_PRECOND, dev, g, noswap, p, and QIODevice::write().
01039 { 01040 CHECK_STREAM_PRECOND(*this) 01041 float g = f; // fixes float-on-stack problem 01042 if (noswap) { // no conversion needed 01043 dev->write((char *)&g, sizeof(float)); 01044 } else { // swap bytes 01045 register uchar *p = (uchar *)(&g); 01046 char b[4]; 01047 b[3] = *p++; 01048 b[2] = *p++; 01049 b[1] = *p++; 01050 b[0] = *p; 01051 dev->write(b, 4); 01052 } 01053 return *this; 01054 }
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| QDataStream & QDataStream::operator<< | ( | double | f | ) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Writes a 64-bit floating point number, f, to the stream using the standard IEEE 754 format. Returns a reference to the stream.
Definition at line 1064 of file qdatastream.cpp.
References b, CHECK_STREAM_PRECOND, dev, noswap, p, and QIODevice::write().
01065 { 01066 CHECK_STREAM_PRECOND(*this) 01067 if (noswap) { 01068 dev->write((char *)&f, sizeof(double)); 01069 } else { 01070 register uchar *p = (uchar *)(&f); 01071 char b[8]; 01072 b[7] = *p++; 01073 b[6] = *p++; 01074 b[5] = *p++; 01075 b[4] = *p++; 01076 b[3] = *p++; 01077 b[2] = *p++; 01078 b[1] = *p++; 01079 b[0] = *p; 01080 dev->write(b, 8); 01081 } 01082 return *this; 01083 }
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| QDataStream & QDataStream::operator<< | ( | const char * | s | ) |
This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts. Writes the ''-terminated string s to the stream and returns a reference to the stream.
The string is serialized using writeBytes().
Definition at line 1095 of file qdatastream.cpp.
References len, qstrlen(), and writeRawData().
01096 { 01097 if (!s) { 01098 *this << (quint32)0; 01099 return *this; 01100 } 01101 uint len = qstrlen(s) + 1; // also write null terminator 01102 *this << (quint32)len; // write length specifier 01103 writeRawData(s, len); 01104 return *this; 01105 }
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| QDataStream & QDataStream::readBytes | ( | char *& | s, | |
| uint & | l | |||
| ) |
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.
Definition at line 837 of file qdatastream.cpp.
References CHECK_STREAM_PRECOND, dev, len, qMin(), QIODevice::read(), ReadPastEnd, and setStatus().
Referenced by operator>>().
00838 { 00839 s = 0; 00840 l = 0; 00841 CHECK_STREAM_PRECOND(*this) 00842 00843 quint32 len; 00844 *this >> len; 00845 if (len == 0) 00846 return *this; 00847 00848 const quint32 Step = 1024 * 1024; 00849 quint32 allocated = 0; 00850 char *prevBuf = 0; 00851 char *curBuf = 0; 00852 00853 do { 00854 int blockSize = qMin(Step, len - allocated); 00855 prevBuf = curBuf; 00856 curBuf = new char[allocated + blockSize + 1]; 00857 if (prevBuf) { 00858 memcpy(curBuf, prevBuf, allocated); 00859 delete [] prevBuf; 00860 } 00861 if (dev->read(curBuf + allocated, blockSize) != blockSize) { 00862 delete [] curBuf; 00863 setStatus(ReadPastEnd); 00864 return *this; 00865 } 00866 allocated += blockSize; 00867 } while (allocated < len); 00868 00869 s = curBuf; 00870 s[len] = '\0'; 00871 l = (uint)len; 00872 return *this; 00873 }
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| int QDataStream::readRawData | ( | char * | s, | |
| int | len | |||
| ) |
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.
Definition at line 884 of file qdatastream.cpp.
References CHECK_STREAM_PRECOND, dev, and QIODevice::read().
Referenced by QByteArray::operator>>(), and operator>>().
00885 { 00886 CHECK_STREAM_PRECOND(-1) 00887 return dev->read(s, len); 00888 }
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| QDataStream & QDataStream::writeBytes | ( | const char * | s, | |
| uint | len | |||
| ) |
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.
Definition at line 1118 of file qdatastream.cpp.
References CHECK_STREAM_PRECOND, and writeRawData().
Referenced by QByteArray::operator<<(), and operator<<().
01119 { 01120 CHECK_STREAM_PRECOND(*this) 01121 *this << (quint32)len; // write length specifier 01122 if (len) 01123 writeRawData(s, len); 01124 return *this; 01125 }
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| int QDataStream::writeRawData | ( | const char * | s, | |
| int | len | |||
| ) |
Writes len bytes from s to the stream. Returns the number of bytes actually written, or -1 on error. The data is not encoded.
Definition at line 1136 of file qdatastream.cpp.
References CHECK_STREAM_PRECOND, dev, and QIODevice::write().
Referenced by operator<<(), writeBytes(), QPdfEnginePrivate::writeCompressed(), and QPdfEnginePrivate::xprintf().
01137 { 01138 CHECK_STREAM_PRECOND(-1) 01139 return dev->write(s, len); 01140 }
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| int QDataStream::skipRawData | ( | int | len | ) |
This is equivalent to calling readRawData() on a buffer of length len and ignoring the buffer.
Definition at line 1153 of file qdatastream.cpp.
References buf, CHECK_STREAM_PRECOND, dev, QIODevice::isSequential(), n, QIODevice::pos(), qMin(), QIODevice::read(), QIODevice::seek(), and QIODevice::size().
01154 { 01155 CHECK_STREAM_PRECOND(-1) 01156 01157 if (dev->isSequential()) { 01158 char buf[4096]; 01159 int sumRead = 0; 01160 01161 while (len > 0) { 01162 int blockSize = qMin(len, (int)sizeof(buf)); 01163 int n = dev->read(buf, blockSize); 01164 if (n == -1) 01165 return -1; 01166 if (n == 0) 01167 return sumRead; 01168 01169 sumRead += n; 01170 len -= blockSize; 01171 } 01172 return sumRead; 01173 } else { 01174 quint64 pos = dev->pos(); 01175 len = qMin(int(dev->size() - pos), len); 01176 if (!dev->seek(pos + len)) 01177 return -1; 01178 return len; 01179 } 01180 }
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QDataStreamPrivate* QDataStream::d [private] |
QIODevice* QDataStream::dev [private] |
Definition at line 157 of file qdatastream.h.
Referenced by atEnd(), operator<<(), operator>>(), QDataStream(), readBytes(), readRawData(), setDevice(), skipRawData(), writeRawData(), and ~QDataStream().
bool QDataStream::owndev [private] |
Definition at line 158 of file qdatastream.h.
Referenced by QDataStream(), setDevice(), and ~QDataStream().
bool QDataStream::noswap [private] |
Definition at line 159 of file qdatastream.h.
Referenced by operator<<(), operator>>(), QDataStream(), and setByteOrder().
ByteOrder QDataStream::byteorder [private] |
Definition at line 160 of file qdatastream.h.
Referenced by byteOrder(), QDataStream(), and setByteOrder().
int QDataStream::ver [private] |
Definition at line 161 of file qdatastream.h.
Referenced by QDataStream(), setVersion(), and version().
Status QDataStream::q_status [private] |
Definition at line 162 of file qdatastream.h.
Referenced by QDataStream(), resetStatus(), setStatus(), and status().
1.5.1