Random integers

Back to The seed. Forward to Random real numbers. Up to Contents.

The following routines return random integers of the given type uniformly distributed in [min, max]. These are member functions of Random. Here IntType is any integer type, b, the bitcount, is an integer, w = Random::width. For the a 32-bit (resp. 64-bit) random generator, result_type is an unsigned int (resp. unsigned long long int) and w = 32 (resp. 64). The "C" in IntegerC stands for "closed".

Definitions of routines returning integers

routine	type	min	max
Integer<IntType, b>()	IntType	0	2b − 1
Integer<b>()	unsigned	0	2b − 1
Integer();	unsigned	0	std::numeric_limits<unsigned>::max()
Integer<IntType>()	IntType	std::numeric_limits<IntType>::min()	std::numeric_limits<IntType>::max()
Boolean()	bool	false	true
Integer<IntType>(IntType n)	IntType	0	n − 1 (if n = 0, std::numeric_limits<IntType>::max(); if n < 0, 0)
IntegerC<IntType>(IntType n)	IntType	0	n (if n < 0, 0)
IntegerC<IntType>(IntType m, IntType n)	IntType	m	n (if n < m, m)
operator()()	Random::result_type	0	2w − 1
operator()(result_type n)	Random::result_type	0	n − 1 (if n = 0, std::numeric_limits<result_type>::max())

Here are some examples of calling these routines

RandomLib::Random r; r.Reseed();
r();                          // unsigned in [0, 2^32)
r(52);                        // unsigned in [0, 52)
r.Integer();                  // unsigned in [0, 2^32)
r.Integer<int>();             // int in [-2^31, 2^31)
r.Integer<unsigned char>();   // unsigned char in [0, 256)
r.Integer<8>();               // unsigned in [0, 256)
r.Integer<int, 8>();          // int in [0, 256)
r.Boolean();                  // boolean in [false, true]
r.Integer(52);                // int in [0, 52)
r.Integer(52u);               // unsigned in [0, 52)
r.IntegerC(51);               // int in [0, 51]
r.IntegerC(1,52);             // int in [1, 52]

Back to The seed. Forward to Random real numbers. Up to Contents.