Standard library header <istream>

C++

Language

Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

Standard Library header files

Language Support
<cstddef> <limits> <climits> <contract>	<cfloat> <cstdint> <new> <version>	<typeinfo> <exception> <initializer_list>	<csignal> <csetjmp> <cstdarg>
Concepts
<concepts>
Diagnostics
<stdexcept>	<cassert>	<cerrno>	<system_error>
General utilities
<utility> <memory> <memory_resource> <scoped_allocator> <compare>	<bitset> <tuple> <optional> <any> <variant>	<type_traits> <ratio> <chrono> <typeindex> <functional>	<ctime> <cstdlib>
Strings
<string> <string_view>	<cctype> <cwctype>	<cwchar> <cuchar>	<cstring> <charconv>
Localization
<locale>	<codecvt>	<clocale>
Containers
<span> <array> <vector>	<deque> <forward_list> <list>	<map> <set> <queue>	<unordered_map> <unordered_set> <stack>
Iterators
<iterator>
Algorithms
<algorithm>	<execution>
Numerics
<complex> <random>	<valarray> <numeric>	<cfenv> <cmath>	<bit>
Input/Output
<iosfwd> <ios> <iomanip> <streambuf>	<istream> <ostream> <iostream>	<sstream> <fstream> <syncstream>	<cstdio> <cinttypes> <strstream>
Regular expressions
<regex>
Filesystem support
<filesystem>
Thread support
<thread> <atomic>	<mutex> <shared_mutex>	<condition_variable> <future>
C compatibility
<ciso646> <cstdalign>	<cstdbool> <ccomplex>	<ctgmath>

This header is part of the input/output library.

Classes
basic_istream	wraps a given abstract device (std::basic_streambuf) and provides high-level input interface (class template)
std::istream	basic_istream<char> (typedef)
std::wistream	basic_istream<wchar_t> (typedef)
basic_iostream	wraps a given abstract device (std::basic_streambuf) and provides high-level input/output interface (class template)
std::iostream	basic_iostream<char> (typedef)
std::wiostream	basic_iostream<wchar_t> (typedef)
Functions
operator>>(std::basic_istream)	extracts characters and character arrays (function template)
Manipulators
ws	consumes whitespace (function template)

Synopsis

namespace std {
    template <class charT, class traits = char_traits<charT> >
        class basic_istream;
    typedef basic_istream<char>    istream;
    typedef basic_istream<wchar_t> wistream;

    template <class charT, class traits = char_traits<charT> >
        class basic_iostream;
    typedef basic_istream<char>    iostream;
    typedef basic_istream<wchar_t> wiostream;

    template <class charT, class traits>
        basic_istream<charT,traits>& ws(basic_istream<charT,traits>& is);

    template <class charT, class traits, class T>
        basic_istream<charT, traits>&
        operator>>(basic_istream<charT, traits>&& is, T& x);

    // character extraction templates:
    template<class charT, class traits>
        basic_istream<charT,traits>& operator>>(basic_istream<charT,traits>&, 
                                                charT&);
    template<class traits>
        basic_istream<char,traits>& operator>>(basic_istream<char,traits>&,
                                            unsigned char&);
    template<class traits>
        basic_istream<char,traits>& operator>>(basic_istream<char,traits>&,
                                            signed char&);
    template<class charT, class traits>
        basic_istream<charT,traits>& operator>>(basic_istream<charT,traits>&,
                                                charT*);
    template<class traits>
        basic_istream<char,traits>& operator>>(basic_istream<char,traits>&,
                                            unsigned char*);
    template<class traits>
        basic_istream<char,traits>& operator>>(basic_istream<char,traits>&,
                                            signed char*);

}

Class std::basic_istream

template <class charT, class traits = char_traits<charT> >
class basic_istream : virtual public basic_ios<charT,traits> {
public:
    // types (inherited from basic_ios):
    typedef charT                     char_type;
    typedef typename traits::int_type int_type;
    typedef typename traits::pos_type pos_type;
    typedef typename traits::off_type off_type;
    typedef traits                    traits_type;

    // Constructor/destructor:
    explicit basic_istream(basic_streambuf<char_type,traits>* sb);
    virtual ~basic_istream();

    // Prefix/suffix:
    class sentry;

    // Formatted input:
    basic_istream<charT,traits>& operator>>(
        basic_istream<charT,traits>& (*pf)(basic_istream<charT,traits>&));
    basic_istream<charT,traits>& operator>>(
        basic_ios<charT,traits>& (*pf)(basic_ios<charT,traits>&));
    basic_istream<charT,traits>& operator>>(
        ios_base& (*pf)(ios_base&));

    basic_istream<charT,traits>& operator>>(bool& n);
    basic_istream<charT,traits>& operator>>(short& n);
    basic_istream<charT,traits>& operator>>(unsigned short& n);
    basic_istream<charT,traits>& operator>>(int& n);
    basic_istream<charT,traits>& operator>>(unsigned int& n);
    basic_istream<charT,traits>& operator>>(long& n);
    basic_istream<charT,traits>& operator>>(unsigned long& n);
    basic_istream<charT,traits>& operator>>(long long& n);
    basic_istream<charT,traits>& operator>>(unsigned long long& n);

    basic_istream<charT,traits>& operator>>(float& f);
    basic_istream<charT,traits>& operator>>(double& f);
    basic_istream<charT,traits>& operator>>(long double& f);

    basic_istream<charT,traits>& operator>>(void*& p);
    basic_istream<charT,traits>& operator>>(
        basic_streambuf<char_type,traits>* sb);

    // Unformatted input:
    streamsize gcount() const;
    int_type get();
    basic_istream<charT,traits>& get(char_type& c);
    basic_istream<charT,traits>& get(char_type* s, streamsize n);
    basic_istream<charT,traits>& get(char_type* s, streamsize n,
                                     char_type delim);
    basic_istream<charT,traits>& get(basic_streambuf<char_type,traits>& sb);
    basic_istream<charT,traits>& get(basic_streambuf<char_type,traits>& sb,
                                     char_type delim);

    basic_istream<charT,traits>& getline(char_type* s, streamsize n);
    basic_istream<charT,traits>& getline(char_type* s, streamsize n,
                                         char_type delim);


    basic_istream<charT,traits>& ignore(
        streamsize n = 1, int_type delim = traits::eof());
    int_type                     peek();
    basic_istream<charT,traits>& read    (char_type* s, streamsize n);
    streamsize                   readsome(char_type* s, streamsize n);

    basic_istream<charT,traits>& putback(char_type c);
    basic_istream<charT,traits>& unget();
    int sync();

    pos_type tellg();
    basic_istream<charT,traits>& seekg(pos_type);
    basic_istream<charT,traits>& seekg(off_type, ios_base::seekdir);

protected:
    basic_istream(const basic_istream& rhs) = delete;
    basic_istream(basic_istream&& rhs);

    // Assign/swap:
    basic_istream& operator=(const basic_istream& rhs) = delete;
    basic_istream& operator=(basic_istream&& rhs);
    void swap(basic_istream& rhs);

};

Class std::basic_iostream

template <class charT, class traits = char_traits<charT> >
class basic_iostream :
    public basic_istream<charT,traits>,
    public basic_ostream<charT,traits> {

public:
    // types
    typedef charT                     char_type;
    typedef typename traits::int_type int_type;
    typedef typename traits::pos_type pos_type;
    typedef typename traits::off_type off_type;
    typedef traits                    traits_type;

    // constructor/destructor
    explicit basic_iostream(basic_streambuf<charT,traits>* sb);
    virtual ~basic_iostream();

protected:
    basic_iostream(const basic_iostream& rhs) = delete;
    basic_iostream(basic_iostream&& rhs);

    // assign/swap
    basic_iostream& operator=(const basic_iostream& rhs) = delete;
    basic_iostream& operator=(basic_iostream&& rhs);
    void swap(basic_iostream& rhs);
};