std::basic_ifstream - cppreference.com (original) (raw)

The class template basic_ifstream implements high-level input operations on file-based streams. It interfaces a file-based streambuffer (std::basic_filebuf) with the high-level interface of (std::basic_istream).

A typical implementation of std::basic_ifstream holds only one non-derived data member: an instance of std::basic_filebuf<CharT, Traits>.

Inheritance diagram

Several typedefs for common character types are provided:

Contents

• 1 Member types
• 2 Member functions
  • 2.1 File operations
• 3 Non-member functions
• 4 Inherited from std::basic_istream
  • 4.1 Member functions
    * 4.1.1 Formatted input
    * 4.1.2 Unformatted input
    * 4.1.3 Positioning
    * 4.1.4 Miscellaneous
  • 4.2 Member classes
• 5 Inherited from std::basic_ios
  • 5.1 Member types
  • 5.2 Member functions
    * 5.2.1 State functions
    * 5.2.2 Formatting
    * 5.2.3 Miscellaneous
• 6 Inherited from std::ios_base
  • 6.1 Member functions
    * 6.1.1 Formatting
    * 6.1.2 Locales
    * 6.1.3 Internal extensible array
    * 6.1.4 Miscellaneous
    * 6.1.5 Member classes
  • 6.2 Member types and constants
  • 6.3 Notes
  • 6.4 Example

[edit] Member types

[edit] Member functions

[edit] Non-member functions

Inherited from std::basic_istream

Member functions

Member classes

| | implements basic logic for preparation of the stream for input operations (public member class of std::basic_istream<CharT,Traits>) [edit] | | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

Inherited from std::basic_ios

Member types

Member functions

State functions
good	checks if no error has occurred i.e. I/O operations are available (public member function of std::basic_ios<CharT,Traits>) [edit]
eof	checks if end-of-file has been reached (public member function of std::basic_ios<CharT,Traits>) [edit]
fail	checks if an error has occurred (public member function of std::basic_ios<CharT,Traits>) [edit]
bad	checks if a non-recoverable error has occurred (public member function of std::basic_ios<CharT,Traits>) [edit]
operator!	checks if an error has occurred (synonym of fail()) (public member function of std::basic_ios<CharT,Traits>) [edit]
operator bool	checks if no error has occurred (synonym of ) (public member function of std::basic_ios<CharT,Traits>) [edit]
rdstate	returns state flags (public member function of std::basic_ios<CharT,Traits>) [edit]
setstate	sets state flags (public member function of std::basic_ios<CharT,Traits>) [edit]
clear	modifies state flags (public member function of std::basic_ios<CharT,Traits>) [edit]
Formatting
copyfmt	copies formatting information (public member function of std::basic_ios<CharT,Traits>) [edit]
fill	manages the fill character (public member function of std::basic_ios<CharT,Traits>) [edit]
Miscellaneous
exceptions	manages exception mask (public member function of std::basic_ios<CharT,Traits>) [edit]
imbue	sets the locale (public member function of std::basic_ios<CharT,Traits>) [edit]
rdbuf	manages associated stream buffer (public member function of std::basic_ios<CharT,Traits>) [edit]
tie	manages tied stream (public member function of std::basic_ios<CharT,Traits>) [edit]
narrow	narrows characters (public member function of std::basic_ios<CharT,Traits>) [edit]
widen	widens characters (public member function of std::basic_ios<CharT,Traits>) [edit]

Inherited from std::ios_base

Member functions

[edit] Notes

[edit] Example

#include #include #include   int main() { std::string filename = "Test.b";   // prepare a file to read double d = 3.14; std::ofstream(filename, std::ios::binary) .write(reinterpret_cast<char*>(&d), sizeof d) << 123 << "abc";   // open file for reading std::ifstream istrm(filename, std::ios::binary); if (!istrm.is_open()) std::cout << "failed to open " << filename << '\n'; else { double d; istrm.read(reinterpret_cast<char*>(&d), sizeof d); // binary input int n; std::string s; if (istrm >> n >> s) // text input std::cout << "read back from file: " << d << ' ' << n << ' ' << s << '\n'; } }

Output:

read back from file: 3.14 123 abc