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

From cppreference.com
 
 
Iterator library
Iterator concepts
Iterator primitives
Iterator adaptors
Stream iterators
Iterator customization points
Iterator operations
(C++11)
(C++11)
Range access
(C++11)(C++14)
(C++11)(C++14)
(C++17)(C++20)
(C++14)(C++14)
(C++14)(C++14)
(C++17)
(C++17)
 
 
constexpr istream_iterator();
(1)
istream_iterator( istream_type& stream );
(2)
istream_iterator( const istream_iterator& other ) = default;
(3)
1) 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.
2) 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.
3) Constructs a copy of other. If std::is_trivially_copy_constructible_v<T> is true , this copy constructor is a trivial copy constructor.

[edit] Parameters

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

[edit] Defect reports

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

DR Applied to Behavior as published Correct behavior
P0738R2 C++98 the first read may be deferred to the first dereferencing the first read is performed in the constructor

[edit] Examples

#include <iostream>
#include <iterator>
#include <algorithm>
#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