diff options
Diffstat (limited to 'src/corelib/global/qrandom.cpp')
| -rw-r--r-- | src/corelib/global/qrandom.cpp | 83 |
1 files changed, 18 insertions, 65 deletions
diff --git a/src/corelib/global/qrandom.cpp b/src/corelib/global/qrandom.cpp index ebf9864b15..23e5e499b2 100644 --- a/src/corelib/global/qrandom.cpp +++ b/src/corelib/global/qrandom.cpp @@ -510,9 +510,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel those. The most common way of generating new values is to call the generate(), generate64() or fillRange() functions. One would use it as: - \code - quint32 value = QRandomGenerator::global()->generate(); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 0 Additionally, it provides a floating-point function generateDouble() that returns a number in the range [0, 1) (that is, inclusive of zero and @@ -525,11 +523,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel the numbers generated by the object will always be the same, as in the following example: - \code - QRandomGenerator prng1(1234), prng2(1234); - Q_ASSERT(prng1.generate32() == prng2.generate32()); - Q_ASSERT(prng1.generate64() == prng2.generate64()); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 1 The seed data takes the form of one or more 32-bit words. The ideal seed size is approximately equal to the size of the QRandomGenerator class @@ -552,12 +546,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel For ease of use, QRandomGenerator provides a global object that can be easily used, as in the following example: - \code - int x = QRandomGenerator::global()->generate32(); - int y = QRandomGenerator::global()->generate32(); - int w = QRandomGenerator::global()->bounded(16384); - int h = QRandomGenerator::global()->bounded(16384); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 2 \section1 System-wide random number generator @@ -645,10 +634,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel following code may be used to generate a floating-point number in the range [1, 2.5): - \code - std::uniform_real_distribution dist(1, 2.5); - return dist(*QRandomGenerator::global()); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 3 \sa QRandomGenerator64, qrand() */ @@ -688,10 +674,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel with the same seed value will produce the same number sequence. This constructor is equivalent to: - \code - std::seed_seq sseq(seedBuffer, seedBuffer + len); - QRandomGenerator generator(sseq); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 4 \sa seed(), securelySeeded() */ @@ -705,10 +688,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel with the same seed value will produce the same number sequence. This constructor is equivalent to: - \code - std::seed_seq sseq(begin, end); - QRandomGenerator generator(sseq); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 5 \sa seed(), securelySeeded() */ @@ -828,10 +808,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel Discards the next \a z entries from the sequence. This method is equivalent to calling generate() \a z times and discarding the result, as in: - \code - while (z--) - generator.generate(); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 6 */ /*! @@ -840,9 +817,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel Generates 32-bit quantities and stores them in the range between \a begin and \a end. This function is equivalent to (and is implemented as): - \code - std::generate(begin, end, [this]() { return generate(); }); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 7 This function complies with the requirements for the function \l{http://en.cppreference.com/w/cpp/numeric/random/seed_seq/generate}{\c std::seed_seq::generate}, @@ -853,9 +828,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel 32 bits of data. Any other bits will be zero. To fill the range with 64 bit quantities, one can write: - \code - std::generate(begin, end, []() { return QRandomGenerator::global()->generate64(); }); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 8 If the range refers to contiguous memory (such as an array or the data from a QVector), the fillRange() function may be used too. @@ -882,11 +855,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel For example, to fill a vector of 16 entries with random values, one may write: - \code - QVector<quint32> vector; - vector.resize(16); - QRandomGenerator::fillRange(vector.data(), vector.size()); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 9 \sa generate() */ @@ -901,10 +870,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel For example, to fill generate two 32-bit quantities, one may write: - \code - quint32 array[2]; - QRandomGenerator::fillRange(array); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 10 It would have also been possible to make one call to generate64() and then split the two halves of the 64-bit value. @@ -919,10 +885,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel inclusive of zero and exclusive of 1). This function is equivalent to: - \code - QRandomGenerator64 rd; - return std::generate_canonical<qreal, std::numeric_limits<qreal>::digits>(rd); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 11 The same may also be obtained by using \l{http://en.cppreference.com/w/cpp/numeric/random/uniform_real_distribution}{\c std::uniform_real_distribution} @@ -937,9 +900,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel Generates one random double in the range between 0 (inclusive) and \a highest (exclusive). This function is equivalent to and is implemented as: - \code - return generateDouble() * highest; - \endcode + \snippet code/src_corelib_global_qrandom.cpp 12 \sa generateDouble(), bounded() */ @@ -956,9 +917,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel For example, to obtain a value between 0 and 255 (inclusive), one would write: - \code - quint32 v = QRandomGenerator::bounded(256); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 13 Naturally, the same could also be obtained by masking the result of generate() to only the lower 8 bits. Either solution is as efficient. @@ -995,9 +954,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel For example, to obtain a value between 1000 (incl.) and 2000 (excl.), one would write: - \code - quint32 v = QRandomGenerator::bounded(1000, 2000); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 14 Note that this function cannot be used to obtain values in the full 32-bit @@ -1053,9 +1010,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel For example, the following creates a random RGB color: - \code - return QColor::fromRgb(QRandomGenerator::global()->generate()); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 15 Accesses to this object are thread-safe and it may therefore be used in any thread without locks. The object may also be copied and the sequence @@ -1123,9 +1078,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel set. If you wish to cast the returned value to qint64 and keep it positive, you should mask the sign bit off: - \code - qint64 value = QRandomGenerator64::generate() & std::numeric_limits<qint64>::max(); - \endcode + \snippet code/src_corelib_global_qrandom.cpp 16 \sa QRandomGenerator, QRandomGenerator::generate64() */ @@ -1298,7 +1251,7 @@ struct QRandEngine }; } -#if defined(QT_NO_THREAD) || defined(Q_OS_WIN) +#if defined(Q_OS_WIN) // On Windows srand() and rand() already use Thread-Local-Storage // to store the seed between calls static inline QRandEngine *randTLS() |