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

template< class CharT, class Traits >
friend std::basic_ostream<CharT, Traits>& 
    operator<<( std::basic_ostream<CharT, Traits>& os, 
                const linear_congruential_engine& e );

(1)

(since C++11)

template< class CharT, class Traits >
friend std::basic_istream<CharT, Traits>& 
    operator>>( std::basic_istream<CharT, Traits>& is, 
                linear_congruential_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) Constant.

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

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/cpp/numeric/random/linear_congruential_engine/operator_ltltgtgt