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

✨ std::basic_...eam::is_open(3) — C++ Standard Libary ✨

Okay bestie, this is the C++ Standard Libary manual page for std::basic_...eam::is_open(3) — yes, that's the manual name exactly as the header gives it, and we respect the lore 💅.

---

🌸 NAME 🌸

std::basic_fstream::is_open — literally std::basic_fstream::is_open. That's the name section, and it ate 💖.

---

🦋 Synopsis 🦋

bool is_open() const;

Checks if the file stream has an associated file.

Effectively calls rdbuf()->is_open() ✨.

---

🎀 Parameters 🎀

(none) — no arguments, no stress, just vibes 🫶.

---

💜 Return value 💜

true if the file stream has an associated file, false otherwise. No cap 🧚.

---

🌈 Example 🌈

// Run this code

#include <fstream>
#include <iostream>
#include <string>

int main()
{
    std::string filename = "some_file";

    std::fstream fs(filename, std::ios::in);

    std::cout << std::boolalpha;
    std::cout << "fs.is_open() = " << fs.is_open() << '\n';

    if (!fs.is_open())
    {
        fs.clear();
        fs.open(filename, std::ios::out);
        std::cout << "fs.is_open() = " << fs.is_open() << '\n';
    }
}

💖 Possible output 💖

fs.is_open() = false
fs.is_open() = true

---

👑 Defect reports 👑

The following behavior-changing defect reports were applied retroactively to previously published C++ standards. Historical receipts, fr fr:

• DR LWG 365 — applied to C++98; behavior as published: is_open was not declared with const qualifier; correct behavior: declared with const qualifier.

---

⭐ See also ⭐

• open — opens a file and associates it with the stream (public member function).
• close — closes the associated file (public member function).

---

Source/version/date tea ☕: http://cppreference.com • 2024.06.10 • std::basic_...eam::is_open(3). That's the footer, bestie — now go check that stream and slay 💖✨