operator<<,>>(std::mersenne_twister_engine)

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Numerics library

Common mathematical functions
Mathematical special functions (C++17)
Mathematical constants (C++20)
Basic linear algebra algorithms (C++26)
Floating-point environment (C++11)
Complex numbers
Numeric array (valarray)
Pseudo-random number generation
Factor operations
gcd (C++17)	lcm (C++17)
Interpolations
midpoint (C++20)	lerp (C++20)
Saturation arithmetic
add_sat (C++26) sub_sat (C++26) saturate_cast (C++26)	mul_sat (C++26) div_sat (C++26)
Generic numeric operations
iota (C++11) ranges::iota (C++23) accumulate inner_product adjacent_difference partial_sum	reduce (C++17) transform_reduce (C++17) inclusive_scan (C++17) exclusive_scan (C++17) transform_inclusive_scan (C++17) transform_exclusive_scan (C++17)
Bit operations
has_single_bit (C++20)     bit_cast (C++20) bit_ceil (C++20) bit_floor (C++20) bit_width (C++20) rotl (C++20) rotr (C++20)	popcount (C++20) countl_zero (C++20) countl_one (C++20) countr_zero (C++20) countr_one (C++20) byteswap (C++23) endian (C++20)

 

Pseudo-random number generation

Uniform random bit generators   uniform_random_bit_generator (C++20) Random number engines linear_congruential_engine (C++11) mersenne_twister_engine (C++11) subtract_with_carry_engine (C++11) philox_engine (C++26) Random number engine adaptors discard_block_engine (C++11) independent_bits_engine (C++11) shuffle_order_engine (C++11) Predefined random number generators Non-deterministic random numbers random_device (C++11) Utilities generate_canonical (C++11) seed_seq (C++11) Random number algorithms ranges::generate_random (C++26) C random library rand    srand    RAND_MAX

Random number distributions Uniform distributions uniform_int_distribution (C++11) uniform_real_distribution (C++11) generate_canonical (C++11) Bernoulli distributions bernoulli_distribution (C++11) binomial_distribution (C++11) negative_binomial_distribution (C++11) geometric_distribution (C++11) Poisson distributions poisson_distribution (C++11) exponential_distribution (C++11) gamma_distribution (C++11) weibull_distribution (C++11) extreme_value_distribution (C++11) Normal distributions normal_distribution (C++11) lognormal_distribution (C++11) chi_squared_distribution (C++11) cauchy_distribution (C++11) fisher_f_distribution (C++11) student_t_distribution (C++11) Sampling distributions discrete_distribution (C++11) piecewise_constant_distribution (C++11) piecewise_linear_distribution (C++11)

 

std::mersenne_twister_engine

Member functions

mersenne_twister_engine::mersenne_twister_engine

mersenne_twister_engine::seed

Generation

mersenne_twister_engine::operator()

mersenne_twister_engine::discard

Characteristics

mersenne_twister_engine::min

mersenne_twister_engine::max

Non-member functions

operator==operator!= (C++11)(C++11)(until C++20)

operator<<operator>> (C++11)(C++11)

 

template< class CharT, class Traits > friend std::basic_ostream<CharT, Traits>&     operator<<( std::basic_ostream<CharT, Traits>& os,                 const mersenne_twister_engine& e );	(1)	(since C++11)
template< class CharT, class Traits > friend std::basic_istream<CharT, Traits>&     operator>>( std::basic_istream<CharT, Traits>& is,                 mersenne_twister_engine& e );	(2)	(since C++11)

1) Writes the textual representation of the current state of e to os with fmtflags set to std::ios_base::dec | std::ios_base::left and the fill character set to the space character.

After writing, os's original fmtflags and fill character are restored.

2) Reads a textual representation of engine state from is (denoted as text) with fmtflags set to std::ios_base::dec, and sets the state of e to that state.

After reading, is's original fmtflags is restored.

• If text was not previously written using an output stream pr, the behavior is undefined.
• Otherwise, if any of the following values is false, the behavior is undefined:

• is.getloc() == pr.getloc()
• std::is_same<decltype(is)::char_type,
               decltype(pr)::char_type>::value
• std::is_same<decltype(is)::traits_type,
               decltype(pr)::traits_type>::value

• Otherwise, if text is not a valid textual representation of any state of decltype(e), the state of e is unchanged and is.setstate(std::ios_base::failbit) is called.
• Otherwise, given another engine eng of the same type as e. If text was previously written by pr << eng and there is no intervening invocations of e or of eng between pr << eng and is >> e, e == eng is true.

These function templates are not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when decltype(e) is an associated class of the arguments.

Parameters

os	-	output stream to insert the data to
is	-	input stream to extract the data from
e	-	pseudo-random number engine

Return value

1) os

2) is

Complexity

1,2) \(\scriptsize O(n) \)O(n).

Exceptions

2) May throw std::ios_base::failure when setting std::ios_base::failbit.

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 3519	C++11	the form of insertion and extraction operators were unspecified	specified to be hidden friends