patterncppMinor

begin and end overloads for istream_iterator

Submitted by: @import:stackexchange-codereview·Mar 10, 2026·

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istream_iteratorforendandoverloadsbegin

Problem

I wrote this pretty straight forward begin and end overloads for istream_iterator.

Is this standards compliant? Any problems with usage?

#include 
#include 
#include 

namespace std
{

    template 
    std::istream_iterator begin(std::istream_iterator iter)
    {
        return iter;
    }

    template 
    std::istream_iterator end(std::istream_iterator)
    {
        return std::istream_iterator();
    }

}

int main()
{
    for (std::string s : std::istream_iterator(std::cin))
    {
        std::cout << s;
    }
}

Solution

Not sure that's how I would have written in.

Its not normal to call std::begin() and std::end() on an iterator.

I would have arranged for a some type to represent the stream as a container:

#include 
#include 
#include 

namespace ThorsAnvil
{
    template
    struct StreamAsContainer
    {
        std::istream& str;
        StreamAsContainer(std::istream& str) : str(str) {}
    };

    template 
    std::istream_iterator begin(StreamAsContainer& c)
    {
        return std::istream_iterator(c.str);
    }

    template 
    std::istream_iterator end(StreamAsContainer&)
    {
        return std::istream_iterator();
    }

}

int main()
{
    namespace TA=ThorsAnvil;
    for (std::string s : TA::StreamAsContainer(std::cin))
    {
        std::cout << s;
    }
}

Code Snippets

#include <iostream>
#include <iterator>
#include <fstream>

namespace ThorsAnvil
{
    template<typename T>
    struct StreamAsContainer
    {
        std::istream& str;
        StreamAsContainer(std::istream& str) : str(str) {}
    };

    template <typename T>
    std::istream_iterator<T> begin(StreamAsContainer<T>& c)
    {
        return std::istream_iterator<T>(c.str);
    }

    template <typename T>
    std::istream_iterator<T> end(StreamAsContainer<T>&)
    {
        return std::istream_iterator<T>();
    }

}

int main()
{
    namespace TA=ThorsAnvil;
    for (std::string s : TA::StreamAsContainer<std::string>(std::cin))
    {
        std::cout << s;
    }
}

Context

StackExchange Code Review Q#105050, answer score: 4

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