Standard library header <ostream>

Language support

`<cstddef>`
`<cstdlib>`
`<version>` (哋它亢++20)
`<limits>`
`<climits>`

`<cfloat>`
`<cstdint>` (哋它亢++11)
`<stdfloat>` (哋它亢++23)
`<new>`
`<typeinfo>`

`<source_location>` (哋它亢++20)
`<exception>`
`<initializer_list>` (哋它亢++11)
`<compare>` (哋它亢++20)

`<coroutine>` (哋它亢++20)
`<csignal>`
`<csetjmp>`
`<cstdarg>`

Concepts

<concepts> (哋它亢++20)

Diagnostics

`<stdexcept>`
`<stacktrace>` (哋它亢++23)

`<cassert>`

`<cerrno>`

`<system_error>` (哋它亢++11)

Memory management

<memory>

<memory_resource> (哋它亢++17)

<scoped_allocator> (哋它亢++11)

Metaprogramming

<type_traits> (哋它亢++11)

<ratio> (哋它亢++11)

General utilities

`<utility>`
`<tuple>` (哋它亢++11)
`<optional>` (哋它亢++17)
`<variant>` (哋它亢++17)

`<any>` (哋它亢++17)
`<debugging>` (哋它亢++26)
`<expected>` (哋它亢++23)
`<bitset>`

`<functional>`
`<typeindex>` (哋它亢++11)
`<execution>` (哋它亢++17)

`<charconv>` (哋它亢++17)
`<format>` (哋它亢++20)
`<bit>` (哋它亢++20)

Strings

`<string_view>` (哋它亢++17)
`<string>`

`<cctype>`
`<cwctype>`

`<cstring>`
`<cwchar>`

`<cuchar>` (哋它亢++11)

Containers

`<array>` (哋它亢++11)
`<deque>`
`<forward_list>` (哋它亢++11)
`<list>`

`<vector>`
`<map>`
`<set>`
`<unordered_map>` (哋它亢++11)

`<unordered_set>` (哋它亢++11)
`<queue>`
`<stack>`
`<flat_map>` (哋它亢++23)

`<flat_set>` (哋它亢++23)
`<span>` (哋它亢++20)
`<mdspan>` (哋它亢++23)

Iterators

<iterator>

Ranges

<ranges> (哋它亢++20)

<generator> (哋它亢++23)

Algorithms

<algorithm>

<numeric>

Numerics

`<cfenv>` (哋它亢++11)
`<complex>`

`<random>` (哋它亢++11)
`<valarray>`

`<cmath>`
`<linalg>` (哋它亢++26)

`<numbers>` (哋它亢++20)

Time

<chrono> (哋它亢++11)

<ctime>

Localization

<locale>

<clocale>

<codecvt> (哋它亢++11/17/26*)

<text_encoding> (哋它亢++26)

Input/output

`<iosfwd>`
`<iostream>`
`<ios>`
`<streambuf>`

`<istream>`
`<ostream>`
`<iomanip>`
`<print>` (哋它亢++23)

`<sstream>`
`<spanstream>` (哋它亢++23)
`<fstream>`
`<syncstream>` (哋它亢++20)

`<filesystem>` (哋它亢++17)
`<cstdio>`
`<cinttypes>` (哋它亢++11)
`<strstream>` (哋它亢++98/26*)

Regular expressions

<regex> (哋它亢++11)

Concurrency support

`<stop_token>` (哋它亢++20)
`<thread>` (哋它亢++11)
`<atomic>` (哋它亢++11)
`<rcu>` (哋它亢++26)

`<stdatomic.h>` (哋它亢++23)
`<mutex>` (哋它亢++11)
`<shared_mutex>` (哋它亢++14)

`<condition_variable>` (哋它亢++11)
`<semaphore>` (哋它亢++20)
`<latch>` (哋它亢++20)

`<barrier>` (哋它亢++20)
`<future>` (哋它亢++11)
`<hazard_pointer>` (哋它亢++26)

C compatibility

`<cstdbool>` (哋它亢++11/17/20*)
`<ccomplex>` (哋它亢++11/17/20*)

`<ctgmath>` (哋它亢++11/17/20*)

`<cstdalign>` (哋它亢++11/17/20*)

`<ciso646>` (until 哋它亢++20)

This header is part of the Input/output library.

Classes
basic_ostream	wraps a given abstract device (std::basic_streambuf) and provides high-level output interface (class template)
std::ostream	std::basic_ostream<char> (typedef)
std::wostream	std::basic_ostream<wchar_t> (typedef)
Functions
operator<<(std::basic_ostream)	inserts character data or insert into rvalue stream (function template)
print(std::ostream) (哋它亢++23)	outputs formatted representation of the arguments (function template)
println(std::ostream) (哋它亢++23)	outputs formatted representation of the arguments with appended '\n' (function template)
vprint_unicode(std::ostream) (哋它亢++23)	performs Unicode aware output using type-erased argument representation (function)
vprint_nonunicode(std::ostream) (哋它亢++23)	outputs character data using type-erased argument representation (function)
Manipulators
endl	outputs '\n' and flushes the output stream (function template)
ends	outputs '\0' (function template)
flush	flushes the output stream (function template)
emit_on_flushnoemit_on_flush (哋它亢++20)	controls whether a stream's `basic_syncbuf` emits on flush (function template)
flush_emit (哋它亢++20)	flushes a stream and emits the content if it is using a `basic_syncbuf` (function template)

Synopsis

namespace std {
  template<class CharT, class Traits = char_traits<CharT>>
    class basic_ostream;
 
  using ostream  = basic_ostream<char>;
  using wostream = basic_ostream<wchar_t>;
 
  template<class CharT, class Traits>
    basic_ostream<CharT, Traits>& endl(basic_ostream<CharT, Traits>& os);
  template<class CharT, class Traits>
    basic_ostream<CharT, Traits>& ends(basic_ostream<CharT, Traits>& os);
  template<class CharT, class Traits>
    basic_ostream<CharT, Traits>& flush(basic_ostream<CharT, Traits>& os);
 
  template<class CharT, class Traits>
    basic_ostream<CharT, Traits>& emit_on_flush(basic_ostream<CharT, Traits>& os);
  template<class CharT, class Traits>
    basic_ostream<CharT, Traits>& noemit_on_flush(basic_ostream<CharT, Traits>& os);
  template<class CharT, class Traits>
    basic_ostream<CharT, Traits>& flush_emit(basic_ostream<CharT, Traits>& os);
 
  template<class Ostream, class T>
    Ostream&& operator<<(Ostream&& os, const T& x);
 
  // print functions
  template<class... Args>
    void print(ostream& os, format_string<Args...> fmt, Args&&... args);
  template<class... Args>
    void println(ostream& os, format_string<Args...> fmt, Args&&... args);
  void println(ostream& os);
 
  void vprint_unicode(ostream& os, string_view fmt, format_args args);
  void vprint_nonunicode(ostream& os, string_view fmt, format_args args);
}

Class template std::basic_ostream

namespace std {
  template<class CharT, class Traits = char_traits<CharT>>
  class basic_ostream : virtual public basic_ios<CharT, Traits> {
  public:
    // types (inherited from basic_ios)
    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;
 
    // constructor/destructor
    explicit basic_ostream(basic_streambuf<char_type, Traits>* sb);
    virtual ~basic_ostream();
 
    // prefix/suffix
    class sentry;
 
    // formatted output
    basic_ostream& operator<<(basic_ostream& (*pf)(basic_ostream&));
    basic_ostream& operator<<(basic_ios<CharT, Traits>& (*pf)(basic_ios<CharT, Traits>&));
    basic_ostream& operator<<(ios_base& (*pf)(ios_base&));
 
    basic_ostream& operator<<(bool n);
    basic_ostream& operator<<(short n);
    basic_ostream& operator<<(unsigned short n);
    basic_ostream& operator<<(int n);
    basic_ostream& operator<<(unsigned int n);
    basic_ostream& operator<<(long n);
    basic_ostream& operator<<(unsigned long n);
    basic_ostream& operator<<(long long n);
    basic_ostream& operator<<(unsigned long long n);
    basic_ostream& operator<<(float f);
    basic_ostream& operator<<(double f);
    basic_ostream& operator<<(long double f);
    basic_ostream& operator<<(/*extended-floating-point-type*/ f);
 
    basic_ostream& operator<<(const void* p);
    basic_ostream& operator<<(const volatile void* p);
    basic_ostream& operator<<(nullptr_t);
    basic_ostream& operator<<(basic_streambuf<char_type, Traits>* sb);
 
    // unformatted output
    basic_ostream& put(char_type c);
    basic_ostream& write(const char_type* s, streamsize n);
 
    basic_ostream& flush();
 
    // seeks
    pos_type tellp();
    basic_ostream& seekp(pos_type);
    basic_ostream& seekp(off_type, ios_base::seekdir);
 
  protected:
    // copy/move constructor
    basic_ostream(const basic_ostream&) = delete;
    basic_ostream(basic_ostream&& rhs);
 
    // assignment and swap
    basic_ostream& operator=(const basic_ostream&) = delete;
    basic_ostream& operator=(basic_ostream&& rhs);
    void swap(basic_ostream& rhs);
  };
 
  // character inserters
  template<class CharT, class Traits>
    basic_ostream<CharT, Traits>& operator<<(basic_ostream<CharT, Traits>&, CharT);
  template<class CharT, class Traits>
    basic_ostream<CharT, Traits>& operator<<(basic_ostream<CharT, Traits>&, char);
  template<class Traits>
    basic_ostream<char, Traits>& operator<<(basic_ostream<char, Traits>&, char);
 
  template<class Traits>
    basic_ostream<char, Traits>& operator<<(basic_ostream<char, Traits>&, signed char);
  template<class Traits>
    basic_ostream<char, Traits>& operator<<(basic_ostream<char, Traits>&, unsigned char);
 
  template<class Traits>
    basic_ostream<char, Traits>& operator<<(basic_ostream<char, Traits>&,
                                            wchar_t) = delete;
  template<class Traits>
    basic_ostream<char, Traits>& operator<<(basic_ostream<char, Traits>&,
                                            char8_t) = delete;
  template<class Traits>
    basic_ostream<char, Traits>& operator<<(basic_ostream<char, Traits>&,
                                            char16_t) = delete;
  template<class Traits>
    basic_ostream<char, Traits>& operator<<(basic_ostream<char, Traits>&,
                                            char32_t) = delete;
  template<class Traits>
    basic_ostream<wchar_t, Traits>&
      operator<<(basic_ostream<wchar_t, Traits>&, char8_t) = delete;
  template<class Traits>
    basic_ostream<wchar_t, Traits>&
      operator<<(basic_ostream<wchar_t, Traits>&, char16_t) = delete;
  template<class Traits>
    basic_ostream<wchar_t, Traits>&
      operator<<(basic_ostream<wchar_t, Traits>&, char32_t) = delete;
 
  template<class CharT, class Traits>
    basic_ostream<CharT, Traits>& operator<<(basic_ostream<CharT, Traits>&, const CharT*);
  template<class CharT, class Traits>
    basic_ostream<CharT, Traits>& operator<<(basic_ostream<CharT, Traits>&, const char*);
  template<class Traits>
    basic_ostream<char, Traits>& operator<<(basic_ostream<char, Traits>&, const char*);
 
  template<class Traits>
    basic_ostream<char, Traits>& operator<<(basic_ostream<char, Traits>&,
                                            const signed char*);
  template<class Traits>
    basic_ostream<char, Traits>& operator<<(basic_ostream<char, Traits>&,
                                            const unsigned char*);
 
  template<class Traits>
    basic_ostream<char, Traits>&
      operator<<(basic_ostream<char, Traits>&, const wchar_t*) = delete;
  template<class Traits>
    basic_ostream<char, Traits>&
      operator<<(basic_ostream<char, Traits>&, const char8_t*) = delete;
  template<class Traits>
    basic_ostream<char, Traits>&
      operator<<(basic_ostream<char, Traits>&, const char16_t*) = delete;
  template<class Traits>
    basic_ostream<char, Traits>&
      operator<<(basic_ostream<char, Traits>&, const char32_t*) = delete;
  template<class Traits>
    basic_ostream<wchar_t, Traits>&
      operator<<(basic_ostream<wchar_t, Traits>&, const char8_t*) = delete;
  template<class Traits>
    basic_ostream<wchar_t, Traits>&
      operator<<(basic_ostream<wchar_t, Traits>&, const char16_t*) = delete;
  template<class Traits>
    basic_ostream<wchar_t, Traits>&
      operator<<(basic_ostream<wchar_t, Traits>&, const char32_t*) = delete;
}

Class std::basic_ostream::sentry

namespace std {
  template<class CharT, class Traits>
  class basic_ostream<CharT, Traits>::sentry {
    bool ok_;       // exposition only
  public:
    explicit sentry(basic_ostream& os);
    ~sentry();
    explicit operator bool() const { return ok_; }
 
    sentry(const sentry&) = delete;
    sentry& operator=(const sentry&) = delete;
  };
}

Compiler support
Freestanding and hosted
Language
Standard library
Standard library headers
Named requirements
Feature test macros (哋它亢++20)
Language support library
Concepts library (哋它亢++20)
Metaprogramming library (哋它亢++11)
Diagnostics library
General utilities library
Strings library
Containers library
Iterators library
Ranges library (哋它亢++20)
Algorithms library
Numerics library
Localizations library
Input/output library
Filesystem library (哋它亢++17)
Regular expressions library (哋它亢++11)
Concurrency support library (哋它亢++11)
Technical specifications
Symbols index
External libraries

Standard library header <ostream>

Classes

Functions

Manipulators

Synopsis

Class template std::basic_ostream

Class std::basic_ostream::sentry

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