diff options
author | Thiago Macieira <thiago.macieira@intel.com> | 2019-03-29 12:49:47 -0700 |
---|---|---|
committer | Thiago Macieira <thiago.macieira@intel.com> | 2019-06-28 23:05:57 -0700 |
commit | 5d7e221bbf9e27e90448243909abc76d81733381 (patch) | |
tree | 0165b5ef03eba0fb2c7dc32562522974c4c7a218 /src | |
parent | 57eed823e412d587e051bff0d4775f08024d4169 (diff) |
QRandomGenerator: assert that bounded() calls have correct arguments
Otherwise, the math will fail badly. Documentation improved to reflect
reality.
Change-Id: I9e3d261ad9bf41cfb2b6fffd159085cd38e3c388
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Diffstat (limited to 'src')
-rw-r--r-- | src/corelib/global/qrandom.cpp | 16 | ||||
-rw-r--r-- | src/corelib/global/qrandom.h | 10 |
2 files changed, 18 insertions, 8 deletions
diff --git a/src/corelib/global/qrandom.cpp b/src/corelib/global/qrandom.cpp index 90df8653a7..bf01b7ae2a 100644 --- a/src/corelib/global/qrandom.cpp +++ b/src/corelib/global/qrandom.cpp @@ -903,6 +903,10 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel \snippet code/src_corelib_global_qrandom.cpp 12 + If the \a highest parameter is negative, the result will be negative too; + if it is infinite or NaN, the result will be infinite or NaN too (that is, + not random). + \sa generateDouble(), bounded() */ @@ -934,7 +938,7 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel \overload Generates one random 32-bit quantity in the range between 0 (inclusive) and - \a highest (exclusive). \a highest must not be negative. + \a highest (exclusive). \a highest must be positive. Note that this function cannot be used to obtain values in the full 32-bit range of int. Instead, use generate() and cast to int. @@ -946,8 +950,11 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel \fn quint32 QRandomGenerator::bounded(quint32 lowest, quint32 highest) \overload - Generates one random 32-bit quantity in the range between \a lowest (inclusive) - and \a highest (exclusive). The same result may also be obtained by using + Generates one random 32-bit quantity in the range between \a lowest + (inclusive) and \a highest (exclusive). The \a highest parameter must be + greater than \a lowest. + + The same result may also be obtained by using \l{http://en.cppreference.com/w/cpp/numeric/random/uniform_int_distribution}{\c std::uniform_int_distribution} with parameters \a lowest and \c{\a highest - 1}. That class can also be used to obtain quantities larger than 32 bits. @@ -968,7 +975,8 @@ inline QRandomGenerator::SystemGenerator &QRandomGenerator::SystemGenerator::sel \overload Generates one random 32-bit quantity in the range between \a lowest - (inclusive) and \a highest (exclusive), both of which may be negative. + (inclusive) and \a highest (exclusive), both of which may be negative, but + \a highest must be greater than \a lowest. Note that this function cannot be used to obtain values in the full 32-bit range of int. Instead, use generate() and cast to int. diff --git a/src/corelib/global/qrandom.h b/src/corelib/global/qrandom.h index 46d3e0e152..260fc1501a 100644 --- a/src/corelib/global/qrandom.h +++ b/src/corelib/global/qrandom.h @@ -122,14 +122,16 @@ public: return quint32(value); } - int bounded(int highest) + quint32 bounded(quint32 lowest, quint32 highest) { - return int(bounded(quint32(highest))); + Q_ASSERT(highest > lowest); + return bounded(highest - lowest) + lowest; } - quint32 bounded(quint32 lowest, quint32 highest) + int bounded(int highest) { - return bounded(highest - lowest) + lowest; + Q_ASSERT(highest > 0); + return int(bounded(0U, quint32(highest))); } int bounded(int lowest, int highest) |