std::basic_...buf::is_open(3)

okay so you clicked into the std::basic_...buf::is_open(3) page from the C++ Standard Libary, and bestie, this one is tiny but important 💅✨

💖 NAME 💖

std::basic_filebuf::is_open - std::basic_filebuf::is_open — yeah, it’s listed twice, and we respect the icon behavior 🫶

✨ Synopsis ✨

Here’s the signature, fresh out of the header:

bool is_open() const;

Returns true if the most recent call to open() succeeded and there has been no call to close() since then. That’s the whole vibe check, fr fr 🌸

🎀 Parameters 🎀

(none) — literally no parameters, zero, nada, no little surprises 🙈

🔥 Return value 🔥

true if the associated file is open, false otherwise. Simple, clean, slay 💖

🌈 Notes 🌈

This function is typically called by std::basic_fstream::is_open() — that’s its little main-character moment, iykyk 👑

💅 Example 💅

Observe the cuteness:

// Run this code

#include <fstream>
#include <iostream>

int main()
{
    std::ifstream fs("test.txt");
    std::filebuf fb;
    fb.open("test.txt", std::ios_base::in);
    std::cout << std::boolalpha
              << "direct call: " << fb.is_open() << '\n'
              << "through streambuf: " << fs.rdbuf()->is_open() << '\n'
              << "through fstream: " << fs.is_open() << '\n';
}

🖥️ Output 🖥️

direct call: true
through streambuf: true
through fstream: true

🦋 See also 🦋

• open — opens a file and configures it as the associated character sequence (public member function)
• close — flushes the put area buffer and closes the associated file (public member function)

💖 sign-off: page std::basic_...buf::is_open(3) · source http://cppreference.com · version/date 2024.06.10 — mwah, go check your is_open() and hydrate, bestie 🧚‍♀️✨