std::istream_iterator<T,CharT,Traits,Distance>:: istream_iterator

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C++
Iterator library
Iterator concepts
Iterator primitives
Algorithm concepts and utilities
Indirect callable concepts
Common algorithm requirements
(C++20)
(C++20)
(C++20)
Utilities
(C++20)
Iterator adaptors
Range access
(C++11) (C++14)
(C++14) (C++14)
(C++11) (C++14)
(C++14) (C++14)
(C++17) (C++20)
(C++17)
(C++17)
std::istream_iterator
(1)
istream_iterator ( ) ;
(until C++11)
constexpr istream_iterator ( ) ;
(since C++11)
constexpr istream_iterator ( std:: default_sentinel_t ) ;
(2) (since C++20)
istream_iterator ( istream_type & stream ) ;
(3)
(4)
istream_iterator ( const istream_iterator & other ) ;
(until C++11)
istream_iterator ( const istream_iterator & other ) = default ;
(since C++11)
1,2) Constructs the end-of-stream iterator , value-initializes the stored value. This constructor is constexpr if the initializer in the definition auto x = T ( ) ; is a constant initializer (since C++11) .
3) Initializes the iterator, stores the address of stream in a data member, and performs the first read from the input stream to initialize the cached value data member.
4) Constructs a copy of other . If std:: is_trivially_copy_constructible < T > :: value is true , this copy constructor is a trivial copy constructor. (since C++11)

Parameters

stream - stream to initialize the istream_iterator with
other - another istream_iterator of the same type

Example

Run this code 
#include <algorithm>
#include <iostream>
#include <iterator>
#include <sstream>
 
int main()
{
    std::istringstream stream("1 2 3 4 5");
    std::copy(
        std::istream_iterator<int>(stream),
        std::istream_iterator<int>(),
        std::ostream_iterator<int>(std::cout, " ")
    );
}

Output: 

1 2 3 4 5

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 1280 C++98 overload (3) stored stream directly stores its address instead
P0738R2 C++98 the first read might be deferred to the first dereference always performed in the constructor
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