default_random_engine

Overview

This is a random number engine class that generates pseudo-random numbers.

Details

Its implementation is platform specific.  Here it's assumed that linear_congruential_engine  is used.

member types

Following properties are defined.

Name	Definition
uint_least32_t result_type	The type of the numbers generated

Constructor

Name

Description

default_random_engine ( result_type val = default_seed ) template <class Sseq> default_random_engine (Sseq& q )

Constructs a linear_congruential_engine object, and initializes its internal state value: The state value is set to val%modulus (unless both val and increment are multiples of modulus, in which case the state value is set to default_seed). The function calls q.generate on a temporary array to construct a single value of type result_type, which is used to initialize the engine as if version (1) was called with it. Example //1 default_random_engine d(21092018u); //2 string s = "Khrisha Rao"; seed_seq seed (s.begin(),s.end()); default_random_engine d2(seed);

Methods

Name	Description
result_type default_random_engine ::min()	Returns the minimum value potentially generated by the random-number engine. Example default_random_engine(); //prints 1 cout << default_random_engine::min() << endl;
result_type default_random_engine ::max()	Returns the maximum value potentially generated by the random-number engine. Example default_random_engine(); //prints 2147483646 cout << default_random_engine::max() << endl;
void seed (result_type val = default_seed ) template <class Sseq> void seed(Sseq& q )	Reinitializes its internal state value: The state value is set to val%modulus (unless both val and increment are multiples of modulus, in which case the state value is set to default_seed). The function calls q.generate on a temporary array to construct a single value of type result_type, which is used to initialize the engine as if version (1) was called with it. Example //1 default_random_engine d; d.seed(21092018u); //2 string s = "Khrisha Rao"; seed_seq seed (s.begin(),s.end()); d.seed(seed);
result_type operator()()	Returns a new random number. The function advances the internal state by one, which modifies the state value. Example default_random_engine d; //prints 16807 cout << d() << endl;
void discard (unsigned long long z)	Advances the internal state by z notches, as if operator() was called z times, but without generating any numbers in the process. The effects on the state sequence are the same as if the transition algorithm was applied as many times as notches advanced. Example default_random_engine d; d.discard(300); //prints 1495170053 cout << d() << endl;

External Methods

Name	Description
ostream& operator<<  (ostream& os, const  default_random_engine& d )	Saves internal state of d to os. Example default_random_engine d(400); stringstream ss; ss << d << endl; //prints 400 cout << d << endl;
istream& operator>> (istream&  is, default_random_engine& d )	Restores internal state of d from is.  Example default_random_engine d(400); stringstream ss; ss << d << endl; //prints 400 cout << d << endl; //prints 400 ss >> d; cout << d << endl;
bool operator== (const default_random_engine&  d,  const  default_random_engine& d2)	Returns true if d and d2 are the same.
bool operator!= (const  default_random_engine& d, const  default_random_engine& d2)	Returns true if d and d2 are not the same.