Movatterモバイル変換

[0]ホーム
URL:

cppreference.com
Namespaces
Variants
    Actions

      std::ios_base

      From cppreference.com
      <cpp‎ |io
       
       
       
       
      Defined in header<ios>
      class ios_base;

      The classios_base is a multipurpose class that serves as the base class for all I/O stream classes. It maintains several kinds of data:

      1) state information: stream status flags.
      2) control information: flags that control formatting of both input and output sequences and the imbued locale.
      3) private storage: indexed extensible data structure that allows bothlong andvoid* members, which may be implemented as two arbitrary-length arrays or a single array of two-element structs or another container.
      4) callbacks: arbitrary number of user-defined functions to be called fromimbue(),std::basic_ios::copyfmt(), and~ios_base().

      Typical implementation holds member constants corresponding to all values offmtflags,iostate,openmode, andseekdir shown below, member variables to maintain current precision, width, and formatting flags, the exception mask, the buffer error state, a resizeable container holding the callbacks, the currently imbued locale, the private storage, and a static integer variable forxalloc().

      Contents

      [edit]Member functions

      constructs the object
      (protected member function)[edit]
      [virtual]
      		 destructs the object
      (virtual public member function)[edit]
      assigns to the stream
      (public member function)[edit]
      Formatting
      manages format flags
      (public member function)[edit]
      sets specific format flag
      (public member function)[edit]
      clears specific format flag
      (public member function)[edit]
      manages decimal precision of floating point operations
      (public member function)[edit]
      manages field width
      (public member function)[edit]
      Locales
      sets locale
      (public member function)[edit]
      returns current locale
      (public member function)[edit]
      Internal extensible array
      [static]
      		 returns a program-wide unique integer that is safe to use as index topword() andiword()
      (public static member function)[edit]
      resizes the private storage if necessary and access to thelong element at the given index
      (public member function)[edit]
      resizes the private storage if necessary and access to thevoid* element at the given index
      (public member function)[edit]
      Miscellaneous
      registers event callback function
      (public member function)[edit]
      sets whether C++ and C I/O libraries are interoperable
      (public static member function)[edit]

      Member classes

      stream exception
      (public member class)[edit]
      initializes standard stream objects
      (public member class)[edit]

      Member types and constants

      Type Explanation
      stream open mode type

      The following constants are also defined:

      Constant Explanation[edit]
      app seek to the end of stream before each write[edit]
      binary open inbinary mode[edit]
      in open for reading[edit]
      out open for writing[edit]
      trunc discard the contents of the stream when opening[edit]
      ate seek to the end of stream immediately after open[edit]
      noreplace(C++23) open in exclusive mode[edit]

      (typedef)[edit]
      formatting flags type

      The following constants are also defined:

      Constant Explanation[edit]
      dec use decimal base for integer I/O: seestd::dec[edit]
      oct use octal base for integer I/O: seestd::oct[edit]
      hex use hexadecimal base for integer I/O: seestd::hex[edit]
      basefielddec| oct| hex. Useful for masking operations[edit]
      left left adjustment (adds fill characters to the right): seestd::left[edit]
      right right adjustment (adds fill characters to the left): seestd::right[edit]
      internal internal adjustment (adds fill characters to the internal designated point): seestd::internal[edit]
      adjustfieldleft| right| internal. Useful for masking operations[edit]
      scientific generate floating point types using scientific notation, or hex notation if combined withfixed: seestd::scientific[edit]
      fixed generate floating point types using fixed notation, or hex notation if combined withscientific: seestd::fixed[edit]
      floatfieldscientific| fixed. Useful for masking operations[edit]
      boolalpha insert and extractbool type in alphanumeric format: seestd::boolalpha[edit]
      showbase generate a prefix indicating the numeric base for integer output, require the currency indicator in monetary I/O: seestd::showbase[edit]
      showpoint generate a decimal-point character unconditionally for floating-point number output: seestd::showpoint[edit]
      showpos generate a+ character for non-negative numeric output: seestd::showpos[edit]
      skipws skip leading whitespace before certain input operations: seestd::skipws[edit]
      unitbuf flush the output after each output operation: seestd::unitbuf[edit]
      uppercase replace certain lowercase letters with their uppercase equivalents in certain output operations: seestd::uppercase[edit]

      (typedef)[edit]
      state of the stream type

      The following constants are also defined:

      Constant Explanation[edit]
      goodbit no error[edit]
      badbit irrecoverable stream error[edit]
      failbit input/output operation failed (formatting or extraction error)[edit]
      eofbit associated input sequence has reached end-of-file[edit]

      (typedef)[edit]
      seeking direction type

      The following constants are also defined:

      Constant Explanation[edit]
      beg the beginning of a stream[edit]
      end the ending of a stream[edit]
      cur the current position of stream position indicator[edit]

      (typedef)[edit]
      specifies event type
      (enum)[edit]
      callback function type
      (typedef)[edit]
      Deprecated member types
      Type Explanation
      io_state(deprecated) integer type that may be used likeiostate
      open_mode(deprecated) integer type that may be used likeopenmode
      seek_dir(deprecated) integer type that may be used likeseekdir
      streamoff(deprecated) unspecified type that may be used likeoff_type, not necessarilystd::streamoff
      streampos(deprecated) unspecified type that may be used likepos_type, not necessarilystd::streampos
      		(until C++17)

      [edit]Defect reports

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

      DRApplied toBehavior as publishedCorrect behavior
      LWG 1357
      (N3110)      		C++98std::ios_base definedoperator~,operator&
      andoperator| for typesopenmode,fmtflags and
      iostate, violating the requirements ofBitmaskType[1]      		removed these definitions
      1. ↑ABitmaskType needs to support bitwise opertaions on its own. The bitwise operation support should not be provided externally.

      [edit]See also

      manages an arbitrary stream buffer
      (class template)[edit]
      Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/io/ios_base&oldid=156251"
      [8]ページ先頭
      ©2009-2025 Movatter.jp