Standard library header <sstream>

 

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Standard library headers

Language support <cfloat> <climits> <compare> (C++20) <coroutine> (C++20) <csetjmp> <csignal> <cstdarg> <cstddef> <cstdint> (C++11) <cstdlib> <exception> <initializer_list> (C++11)    <limits> <new> <source_location> (C++20) <stdfloat> (C++23) <typeinfo> <version> (C++20) Concepts <concepts> (C++20) Diagnostics <cassert> <cerrno> <debugging> (C++26) <stacktrace> (C++23) <stdexcept> <system_error> (C++11) Memory management <memory> <memory_resource> (C++17) <scoped_allocator> (C++11) Metaprogramming <type_traits> (C++11) <ratio> (C++11)

General utilities <any> (C++17) <bitset> <bit> (C++20) <charconv> (C++17) <expected> (C++23) <format> (C++20) <functional> <optional> (C++17) <tuple> (C++11) <typeindex> (C++11) <utility> <variant> (C++17) Containers <array> (C++11) <deque> <flat_map> (C++23) <flat_set> (C++23) <forward_list> (C++11) <inplace_vector> (C++26)    <list> <map> <mdspan> (C++23) <queue> <set> <span> (C++20) <stack> <unordered_map> (C++11) <unordered_set> (C++11) <vector> Iterators <iterator> Ranges <generator> (C++23) <ranges> (C++20)

Algorithms <algorithm> <numeric> Strings <cctype> <cstring> <cuchar> (C++11) <cwchar> <cwctype> <string_view> (C++17) <string> Text processing <clocale> <codecvt> (C++11/17/26*) <locale> <regex> (C++11) <text_encoding> (C++26)    Numerics <cfenv> (C++11) <cmath> <complex> <linalg> (C++26) <numbers> (C++20) <random> (C++11) <valarray> Time <chrono> (C++11) <ctime> C compatibility <ccomplex> (C++11/17/20*) <ciso646> (until C++20) <cstdalign> (C++11/17/20*) <cstdbool> (C++11/17/20*) <ctgmath> (C++11/17/20*)

Input/output <cinttypes> (C++11) <cstdio> <filesystem> (C++17) <fstream> <iomanip> <iosfwd> <iostream> <ios> <istream> <ostream> <print> (C++23) <spanstream> (C++23) <sstream> <streambuf> <strstream> (C++98/26*) <syncstream> (C++20) Concurrency support <atomic> (C++11) <barrier> (C++20) <condition_variable> (C++11) <future> (C++11) <hazard_pointer> (C++26) <latch> (C++20) <mutex> (C++11) <rcu> (C++26) <semaphore> (C++20) <shared_mutex> (C++14) <stdatomic.h> (C++23) <stop_token> (C++20) <thread> (C++11) Execution support <execution> (C++17)

 

This header is part of the Input/Output library.

Classes
basic_stringbuf	implements raw string device (class template)
basic_istringstream	implements high-level string stream input operations (class template)
basic_ostringstream	implements high-level string stream output operations (class template)
basic_stringstream	implements high-level string stream input/output operations (class template)
stringbuf	std::basic_stringbuf<char> (typedef)
wstringbuf	std::basic_stringbuf<wchar_t> (typedef)
istringstream	std::basic_istringstream<char> (typedef)
wistringstream	std::basic_istringstream<wchar_t> (typedef)
ostringstream	std::basic_ostringstream<char> (typedef)
wostringstream	std::basic_ostringstream<wchar_t> (typedef)
stringstream	std::basic_stringstream<char> (typedef)
wstringstream	std::basic_stringstream<wchar_t> (typedef)
Functions
std::swap(std::basic_stringbuf) (C++11)	specializes the std::swap algorithm (function template)
std::swap(std::basic_istringstream) (C++11)	specializes the std::swap algorithm (function template)
std::swap(std::basic_ostringstream) (C++11)	specializes the std::swap algorithm (function template)
std::swap(std::basic_stringstream) (C++11)	specializes the std::swap algorithm (function template)

Synopsis

namespace std {
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
    class basic_stringbuf;
 
  using stringbuf  = basic_stringbuf<char>;
  using wstringbuf = basic_stringbuf<wchar_t>;
 
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
    class basic_istringstream;
 
  using istringstream  = basic_istringstream<char>;
  using wistringstream = basic_istringstream<wchar_t>;
 
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
    class basic_ostringstream;
  using ostringstream  = basic_ostringstream<char>;
  using wostringstream = basic_ostringstream<wchar_t>;
 
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
    class basic_stringstream;
  using stringstream  = basic_stringstream<char>;
  using wstringstream = basic_stringstream<wchar_t>;
}

Class template std::basic_stringbuf

namespace std {
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
  class basic_stringbuf : public basic_streambuf<CharT, Traits> {
  public:
    using char_type      = CharT;
    using int_type       = typename Traits::int_type;
    using pos_type       = typename Traits::pos_type;
    using off_type       = typename Traits::off_type;
    using traits_type    = Traits;
    using allocator_type = Allocator;
 
    // constructors
    basic_stringbuf() : basic_stringbuf(ios_base::in | ios_base::out) {}
    explicit basic_stringbuf(ios_base::openmode which);
    explicit basic_stringbuf(
      const basic_string<CharT, Traits, Allocator>& s,
      ios_base::openmode which = ios_base::in | ios_base::out);
    explicit basic_stringbuf(const Allocator& a)
      : basic_stringbuf(ios_base::in | ios_base::out, a) {}
    basic_stringbuf(ios_base::openmode which, const Allocator& a);
    explicit basic_stringbuf(
      basic_string<CharT, Traits, Allocator>&& s,
      ios_base::openmode which = ios_base::in | ios_base::out);
    template<class SAlloc>
      basic_stringbuf(
        const basic_string<CharT, Traits, SAlloc>& s, const Allocator& a)
        : basic_stringbuf(s, ios_base::in | ios_base::out, a) {}
    template<class SAlloc>
      basic_stringbuf(
        const basic_string<CharT, Traits, SAlloc>& s,
        ios_base::openmode which, const Allocator& a);
    template<class SAlloc>
      explicit basic_stringbuf(
        const basic_string<CharT, Traits, SAlloc>& s,
        ios_base::openmode which = ios_base::in | ios_base::out);
    basic_stringbuf(const basic_stringbuf&) = delete;
    basic_stringbuf(basic_stringbuf&& rhs);
    basic_stringbuf(basic_stringbuf&& rhs, const Allocator& a);
 
    // assign and swap
    basic_stringbuf& operator=(const basic_stringbuf&) = delete;
    basic_stringbuf& operator=(basic_stringbuf&& rhs);
    void swap(basic_stringbuf& rhs) noexcept(see below);
 
    // getters and setters
    allocator_type get_allocator() const noexcept;
 
    basic_string<CharT, Traits, Allocator> str() const &;
    template<class SAlloc>
      basic_string<CharT,Traits,SAlloc> str(const SAlloc& sa) const;
    basic_string<CharT, Traits, Allocator> str() &&;
    basic_string_view<CharT, Traits> view() const noexcept;
 
    void str(const basic_string<CharT, Traits, Allocator>& s);
    template<class SAlloc>
      void str(const basic_string<CharT, Traits, SAlloc>& s);
    void str(basic_string<CharT, Traits, Allocator>&& s);
 
  protected:
    // overridden virtual functions
    int_type underflow() override;
    int_type pbackfail(int_type c = Traits::eof()) override;
    int_type overflow (int_type c = Traits::eof()) override;
    basic_streambuf<CharT, Traits>* setbuf(CharT*, streamsize) override;
 
    pos_type seekoff(off_type off, ios_base::seekdir way,
                     ios_base::openmode which
                      = ios_base::in | ios_base::out) override;
    pos_type seekpos(pos_type sp,
                     ios_base::openmode which
                      = ios_base::in | ios_base::out) override;
 
  private:
    ios_base::openmode mode;                        // exposition only
    basic_string<CharT, Traits, Allocator> buf;     // exposition only
    void init_buf_ptrs();                           // exposition only
  };
 
  template<class CharT, class Traits, class Allocator>
    void swap(basic_stringbuf<CharT, Traits, Allocator>& x,
              basic_stringbuf<CharT, Traits, Allocator>& y) noexcept(noexcept(x.swap(y)));
}

Class template std::basic_istringstream

namespace std {
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
  class basic_istringstream : public basic_istream<CharT, Traits> {
  public:
    using char_type      = CharT;
    using int_type       = typename Traits::int_type;
    using pos_type       = typename Traits::pos_type;
    using off_type       = typename Traits::off_type;
    using traits_type    = Traits;
    using allocator_type = Allocator;
 
    // constructors
    basic_istringstream() : basic_istringstream(ios_base::in) {}
    explicit basic_istringstream(ios_base::openmode which);
    explicit basic_istringstream(
      const basic_string<CharT, Traits, Allocator>& s,
      ios_base::openmode which = ios_base::in);
    basic_istringstream(ios_base::openmode which, const Allocator& a);
    explicit basic_istringstream(
      basic_string<CharT, Traits, Allocator>&& s,
      ios_base::openmode which = ios_base::in);
    template<class SAlloc>
      basic_istringstream(
        const basic_string<CharT, Traits, SAlloc>& s, const Allocator& a)
        : basic_istringstream(s, ios_base::in, a) {}
    template<class SAlloc>
      basic_istringstream(
        const basic_string<CharT, Traits, SAlloc>& s,
        ios_base::openmode which, const Allocator& a);
    template<class SAlloc>
      explicit basic_istringstream(
        const basic_string<CharT, Traits, SAlloc>& s,
        ios_base::openmode which = ios_base::in);
    basic_istringstream(const basic_istringstream&) = delete;
    basic_istringstream(basic_istringstream&& rhs);
 
    // assign and swap
    basic_istringstream& operator=(const basic_istringstream&) = delete;
    basic_istringstream& operator=(basic_istringstream&& rhs);
    void swap(basic_istringstream& rhs);
 
    // members
    basic_stringbuf<CharT, Traits, Allocator>* rdbuf() const;
    basic_string<CharT, Traits, Allocator> str() const &;
    template<class SAlloc>
      basic_string<CharT,Traits,SAlloc> str(const SAlloc& sa) const;
    basic_string<CharT, Traits, Allocator> str() &&;
    basic_string_view<CharT, Traits> view() const noexcept;
 
    void str(const basic_string<CharT, Traits, Allocator>& s);
    template<class SAlloc>
      void str(const basic_string<CharT, Traits, SAlloc>& s);
    void str(basic_string<CharT, Traits, Allocator>&& s);
 
  private:
    basic_stringbuf<CharT, Traits, Allocator> sb;   // exposition only
  };
 
  template<class CharT, class Traits, class Allocator>
    void swap(basic_istringstream<CharT, Traits, Allocator>& x,
              basic_istringstream<CharT, Traits, Allocator>& y);
}

Class template std::basic_ostringstream

namespace std {
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
  class basic_ostringstream : public basic_ostream<CharT, Traits> {
  public:
    using char_type      = CharT;
    using int_type       = typename Traits::int_type;
    using pos_type       = typename Traits::pos_type;
    using off_type       = typename Traits::off_type;
    using traits_type    = Traits;
    using allocator_type = Allocator;
 
    // constructors
    basic_ostringstream() : basic_ostringstream(ios_base::out) {}
    explicit basic_ostringstream(ios_base::openmode which);
    explicit basic_ostringstream(
      const basic_string<CharT, Traits, Allocator>& s,
      ios_base::openmode which = ios_base::out);
    basic_ostringstream(ios_base::openmode which, const Allocator& a);
    explicit basic_ostringstream(
      basic_string<CharT, Traits, Allocator>&& s,
      ios_base::openmode which = ios_base::out);
    template<class SAlloc>
      basic_ostringstream(
        const basic_string<CharT, Traits, SAlloc>& s, const Allocator& a)
        : basic_ostringstream(s, ios_base::out, a) {}
    template<class SAlloc>
      basic_ostringstream(
        const basic_string<CharT, Traits, SAlloc>& s,
        ios_base::openmode which, const Allocator& a);
    template<class SAlloc>
      explicit basic_ostringstream(
        const basic_string<CharT, Traits, SAlloc>& s,
        ios_base::openmode which = ios_base::out);
    basic_ostringstream(const basic_ostringstream&) = delete;
    basic_ostringstream(basic_ostringstream&& rhs);
 
    // assign and swap
    basic_ostringstream& operator=(const basic_ostringstream&) = delete;
    basic_ostringstream& operator=(basic_ostringstream&& rhs);
    void swap(basic_ostringstream& rhs);
 
    // members
    basic_stringbuf<CharT, Traits, Allocator>* rdbuf() const;
 
    basic_string<CharT, Traits, Allocator> str() const &;
    template<class SAlloc>
      basic_string<CharT,Traits,SAlloc> str(const SAlloc& sa) const;
    basic_string<CharT, Traits, Allocator> str() &&;
    basic_string_view<CharT, Traits> view() const noexcept;
 
    void str(const basic_string<CharT, Traits, Allocator>& s);
    template<class SAlloc>
      void str(const basic_string<CharT, Traits, SAlloc>& s);
    void str(basic_string<CharT, Traits, Allocator>&& s);
 
   private:
    basic_stringbuf<CharT, Traits, Allocator> sb;   // exposition only
  };
 
  template<class CharT, class Traits, class Allocator>
    void swap(basic_ostringstream<CharT, Traits, Allocator>& x,
              basic_ostringstream<CharT, Traits, Allocator>& y);
}

Class template std::basic_stringstream

namespace std {
  template<class CharT, class Traits = char_traits<CharT>,
           class Allocator = allocator<CharT>>
  class basic_stringstream : public basic_iostream<CharT, Traits> {
  public:
    using char_type      = CharT;
    using int_type       = typename Traits::int_type;
    using pos_type       = typename Traits::pos_type;
    using off_type       = typename Traits::off_type;
    using traits_type    = Traits;
    using allocator_type = Allocator;
 
    // constructors
    basic_stringstream() : basic_stringstream(ios_base::out | ios_base::in) {}
    explicit basic_stringstream(ios_base::openmode which);
    explicit basic_stringstream(
      const basic_string<CharT, Traits, Allocator>& s,
      ios_base::openmode which = ios_base::out | ios_base::in);
    basic_stringstream(ios_base::openmode which, const Allocator& a);
    explicit basic_stringstream(
      basic_string<CharT, Traits, Allocator>&& s,
      ios_base::openmode which = ios_base::out | ios_base::in);
    template<class SAlloc>
      basic_stringstream(
        const basic_string<CharT, Traits, SAlloc>& s, const Allocator& a)
        : basic_stringstream(s, ios_base::out | ios_base::in, a) {}
    template<class SAlloc>
      basic_stringstream(
        const basic_string<CharT, Traits, SAlloc>& s,
        ios_base::openmode which, const Allocator& a);
    template<class SAlloc>
      explicit basic_stringstream(
        const basic_string<CharT, Traits, SAlloc>& s,
        ios_base::openmode which = ios_base::out | ios_base::in);
    basic_stringstream(const basic_stringstream&) = delete;
    basic_stringstream(basic_stringstream&& rhs);
 
    // assign and swap
    basic_stringstream& operator=(const basic_stringstream&) = delete;
    basic_stringstream& operator=(basic_stringstream&& rhs);
    void swap(basic_stringstream& rhs);
 
    // members
    basic_stringbuf<CharT, Traits, Allocator>* rdbuf() const;
 
    basic_string<CharT, Traits, Allocator> str() const &;
    template<class SAlloc>
      basic_string<CharT,Traits,SAlloc> str(const SAlloc& sa) const;
    basic_string<CharT, Traits, Allocator> str() &&;
    basic_string_view<CharT, Traits> view() const noexcept;
 
    void str(const basic_string<CharT, Traits, Allocator>& s);
    template<class SAlloc>
      void str(const basic_string<CharT, Traits, SAlloc>& s);
    void str(basic_string<CharT, Traits, Allocator>&& s);
 
  private:
    basic_stringbuf<CharT, Traits> sb;  // exposition only
  };
 
  template<class CharT, class Traits, class Allocator>
    void swap(basic_stringstream<CharT, Traits, Allocator>& x,
              basic_stringstream<CharT, Traits, Allocator>& y);
}

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 170	C++98	the definitions of traits_type were missing in the synopses of std::basic_ostringstream and std::basic_stringstream	added
LWG 251	C++98	the definitions of allocator_type were missing in the synopses of std::basic_stringbuf, std::basic_istringstream std::basic_ostringstream and std::basic_stringstream	added