std::basic_ios::basic_ios(3)

🎀 std::basic_ios::basic_ios 🎀

Ok so welcome to the C++ Standard Libary manpage for std::basic_ios::basic_ios(3) — constructor edition, and yes, we are getting into it. 💅

💖 NAME 💖

std::basic_ios::basic_ios — this is the constructor page for std::basic_ios, bestie. That's the name, that's the vibe. 🫶

✨ Synopsis ✨

It literally constructs a new std::basic_ios object. Here's the signature situation, exactly as the manual lays it out:

          protected:                                                     (1)
          basic_ios();
          public:                                                        (2)
          explicit basic_ios( std::basic_streambuf<CharT, Traits>* sb );
          private:
       (until C++11)
          basic_ios( const basic_ios& );                                 (3)
          public:
       (since C++11)
          basic_ios( const basic_ios& ) = delete;

The numbered tea ☕:

1. Default constructor — the internal state is not initialized. init() must be called before the first use of the object or before the destructor, otherwise the behavior is undefined. No cap, that's a real "handle your initialization" warning. 😭
2. basic_ios( std::basic_streambuf<CharT, Traits>* sb ) — initializes the internal state by calling init(sb). The associated stream buffer is set to sb.
3. Copy constructor — it's declared private and not defined (until C++11), and since C++11 it's explicitly defined as deleted. The reason is iconic: I/O streams are not CopyConstructible. Periodt. 💀

🌸 Parameters 🌸

• sb — stream buffer to associate to. That's the whole parameter list, and she's doing her job. 🦋

🎀 Defect reports 🎀

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

• DR LWG 1249 — applied to C++98. Behavior as published: internal state did not need to be initialized before first use. Correct behavior: also needs to be initialized. 💖

💖 that's the whole page, bestie — source: http://cppreference.com, version/date: 2024.06.10. Now go initialize your internal state before first use, fr fr. 💅✨