std::basic_ofstream::open(3)

💖 NAME 💖

std::basic_ofstream::open - std::basic_ofstream::open

okay so this page is std::basic_ofstream::open from the C++ Standard Libary manual (yes, that's literally how the header spells it 😭), and it's lowkey the moment your output file stream gets a file bestie to talk to. ✨

✨ Synopsis ✨

void open( const char* filename,
           std::ios_base::openmode mode                       (1)
               = std::ios_base::out );
void open( const std::filesystem::path::value_type* filename,
           std::ios_base::openmode mode                       (2)
       (since C++17)
               = std::ios_base::out );
void open( const std::string& filename,
           std::ios_base::openmode mode                       (3)
       (since C++11)
               = std::ios_base::out );
void open( const std::filesystem::path& filename,
           std::ios_base::openmode mode                       (4)
       (since C++17)
               = std::ios_base::out );

🎀 Parameters 🎀

• filename — the name of the file to be opened 💅
• mode — specifies stream open mode. It is a BitmaskType, and the following constants are defined:
  • app — seek to the end of stream before each write
  • binary — open in binary mode
  • in — open for reading
  • out — open for writing
  • trunc — discard the contents of the stream when opening
  • ate — seek to the end of stream immediately after open
  • noreplace (C++23) — open in exclusive mode

🦋 Description 🦋

so the whole vibe is: opens and associates the file with name filename with the file stream. that's the main character move. 🌟

then the important little detail, no cap: calls clear() on success. calls setstate(failbit) on failure. 🫶

here's the overload breakdown, bestie:

• 1,2) Effectively calls rdbuf()->open(filename, mode | ios_base::out) (see std::basic_filebuf::open for the details on the effects of that call).
• Overload (2) is only provided if std::filesystem::path::value_type is not char. (since C++17)
• 3,4) Effectively calls (1,2) as if by open(filename.c_str(), mode).

🌸 Return value 🌸

(none) — that's it, that's the return value. iconic minimalism. 💀

🍓 Example 🍓

This section is incomplete.

Reason: no example.

💅 Defect reports 💅

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

• DR LWG 22 — Applied to: C++98; Behavior as published: it was unclear how error state changes upon a successful open; Correct behavior: the error state is unchanged.
• DR LWG 409 — Applied to: C++98; Behavior as published: the error state was unchanged upon a successful open; Correct behavior: it is cleared^[1].

1. ↑ The resolution of LWG issue #22 is overriden.

👑 See also 👑

• is_open — checks if the stream has an associated file (public member function).
• close — closes the associated file (public member function).
• open — opens a file and configures it as the associated character sequence (public member function of std::basic_filebuf<CharT,Traits>).

🍓 Category 🍓

• * Todo no example

bye bestie 💖 — source: http://cppreference.com; version/date: 2024.06.10; page: std::basic_ofstream::open(3).