If that happens, first the operating system then QRandomGenerator will fall back to Pseudo Random Number Generators of decreasing qualities (Qt's fallback generator being the simplest). However, if they are true RNGs, those facilities have finite entropy sources and thus may fail to produce any results if their entropy pool is exhausted. On such systems, those facilities are true Random Number Generators. This function will use hardware facilities to generate random numbers where available. QRandomGenerator::system() may be used to access the system-wide random number generator, which is cryptographically-safe on all systems that Qt runs on. Int h = QRandomGenerator ::global() - >bounded( 16384) System-wide random number generator Int w = QRandomGenerator ::global() - >bounded( 16384) Int y = QRandomGenerator ::global() - >generate() Int x = QRandomGenerator ::global() - >generate() In fact, applications that do not need cryptographically-secure or true random data are advised to use a regular QRandomGenerator instead of QRandomGenerator::system() for their random data needs.įor ease of use, QRandomGenerator provides a global object that can be easily used, as in the following example: When operating in deterministic mode, QRandomGenerator may be used for bulk data generation. QRandomGenerator::global(), like all generators created by QRandomGenerator::securelySeeded(), is always seeded from QRandomGenerator::system(), so it's not possible to make it produce identical sequences. Due to mixing of the seed data, QRandomGenerator cannot guarantee that distinct seeds will produce different sequences. The ideal seed size is approximately equal to the size of the QRandomGenerator class itself. The seed data takes the form of one or more 32-bit words. The most common way of generating new values is to call the generate(), generate64() or fillRange() functions. The class can generate 32-bit or 64-bit quantities, or fill an array of those. On Unix systems, it's equivalent to reading from /dev/urandom or the getrandom() or getentropy() system calls. QRandomGenerator::system() may be used to access the system's cryptographically-safe random generator. This object is thread-safe, may be shared for most uses, and is always seeded from QRandomGenerator::system() Additionally, QRandomGenerator::global() returns a global instance of QRandomGenerator that Qt will ensure to be securely seeded. QRandomGenerator::securelySeeded() can be used to create a QRandomGenerator that is securely seeded with QRandomGenerator::system(), meaning that the sequence of numbers it generates cannot be easily predicted. But given different seeds, the results should be considerably different. That is to say, given the same seed data, QRandomGenerator will generate the same sequence of numbers. When seeded, the sequence of numbers generated by this class is deterministic. Like the C++ random engines, QRandomGenerator can be seeded with user-provided values through the constructor. QRandomGenerator may be used to generate random values from a high-quality random number generator. Generate(ForwardIterator begin, ForwardIterator end) QRandomGenerator(const QRandomGenerator & other)īounded(unsigned int lowest, quint64 highest)īounded(quint64 lowest, unsigned int highest)įillRange(UInt * buffer, qsizetype count) QRandomGenerator(const quint32 * begin, const quint32 * end) QRandomGenerator(const quint32 * seedBuffer, qsizetype len) QRandomGenerator(const quint32 (&) seedBuffer = N)
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |