C++ FAQ / Section 4 / FAQ 4.34

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Revised Jul 4, 2012

[4.34] What updates were made for the 12/02 release?

Big-picture changes:

• Added a new section on Multiple and Virtual Inheritance.
• Added a new section on Serialization.
• Added New! and Updated! tags on the section titles.

34 New FAQs:

• [4.34] What updates were made for the 12/02 release?
  (created)
• [13.14] How can I overload the prefix and postfix forms of operators ++ and --?
  (created thanks to Sandeep Grover)
• [13.15] Which is more efficient: i++ or ++i?
  (created)
• [15.12] How can I open a stream in binary mode?
  (created thanks to Simon Barner)
• [15.14] How can I write/read objects of my class to/from a data file?
  (created)
• [15.15] How can I send objects of my class to another computer (e.g., via a socket, TCP/IP, FTP, email, a wireless link, etc.)?
  (created)
• [19.8] I've been told to never use protected data, and instead to always use private data with protected access functions. Is that a good rule?
  (created thanks to a question from Andrew Chan)
• [19.9] Okay, so exactly how should I decide whether to build a "protected interface"?
  (created)
• [21.11] How could "it depend"??!? Aren't terms like "Circle" and "Ellipse" defined mathematically?
  (created)
• [25.1] How is this section organized?
  (created)
• [25.2] I've been told that I should never use multiple inheritance. Is that right?
  (created)
• [25.3] So there are times when multiple inheritance isn't bad?!??
  (created)
• [25.4] What are some disciplines for using multiple inheritance?
  (created)
• [25.5] Can you provide an example that demonstrates the above guidelines?
  (created)
• [25.6] Is there a simple way to visualize all these tradeoffs?
  (created)
• [25.7] Can you give another example to illustrate the above disciplines?
  (created)
• [25.11] What special considerations do I need to know about when I use virtual inheritance?
  (created)
• [25.12] What special considerations do I need to know about when I inherit from a class that uses virtual inheritance?
  (created)
• [25.13] What special considerations do I need to know about when I use a class that uses virtual inheritance?
  (created)
• [25.14] One more time: what is the exact order of constructors in a multiple and/or virtual inheritance situation?
  (created thanks to Carl Daniel)
• [33.10] Can I convert a pointer-to-member-function to a void*?
  (created)
• [33.11] Can I convert a pointer-to-function to a void*?
  (created)
• [35.13] How can I avoid linker errors with my template functions? Updated!
  (created thanks to a suggestion by Michael Kochetkov)
• [35.15] How can I avoid linker errors with my template classes? Updated!
  (created thanks to a suggestion by Michael Kochetkov)
• [36.1] What's this "serialization" thing all about?
  (created thanks to a question from Stephen Tashiro)
• [36.2] How do I select the best serialization technique?
  (created)
• [36.7] How do I serialize objects that aren't part of an inheritance hierarchy and that don't contain pointers to other objects?
  (created)
• [36.8] How do I serialize objects that are part of an inheritance hierarchy and that don't contain pointers to other objects?
  (created)
• [36.9] How do I serialize objects that contain pointers to other objects, but those pointers form a tree with no cycles and no joins?
  (created)
• [36.10] How do I serialize objects that contain pointers to other objects, but those pointers form a tree with no cycles and only "trivial" joins?
  (created)
• [36.11] How do I serialize objects that contain pointers to other objects, and those pointers form a graph that might have cycles or non-trivial joins?
  (created thanks to a question from Stephen Tashiro)
• [36.12] Are there any caveats when serializing / unserializing objects?
  (created)
• [36.13] What's all this about graphs, trees, nodes, cycles, joins, and joins at the leaves vs. internal nodes?
  (created)
• [39.3] Can I templatize the above functions so they work with other types?
  (inspired by Merlyn Morgan-Graham)

21 Changed FAQs:

• [5.2] How do I get other people to do my homework problem for me?
  (added the "serious bodily harm" quote thanks to Jack Klein)
• [5.4] How can I find out about general netiquette so I don't embarrass myself?
  (added the joke/quote about top-posting)
• [6.15] What does the FAQ mean by "such and such is evil"?
  (fixed a typo in the last paragraph thanks to YaoJun)
• [10.18] Do I need to worry about the "static initialization order fiasco" for variables of built-in/intrinsic types?
  (added std:: prefix on cout thanks to Thomas Tutone)
• [13.1] What's the deal with operator overloading?
  (changed parameter types from by-value to by-reference-to-const)
• [15.13] How can I "reopen" std::cin and std::cout in binary mode?
  (removed references to DOS and OS/2)
• [15.16] Why can't I open a file in a different directory such as "..\test.dat"?
  (moved/renumbered)
• [29.3] Should I use void main() or int main()?
  (fixed parameter-order mistake thanks to Chris Young and many others)
• [29.17] Why doesn't my floating-point comparison work?
  (reworded)
• [33.2] How do I pass a pointer-to-member-function to a signal handler, X event callback, system call that starts a thread/task, etc?
  (shortened some names to make it easier to read)
• [33.5] How can I avoid syntax errors when creating pointers to members?
  (renamed the macro to all-caps)
• [33.6] How can I avoid syntax errors when calling a member function using a pointer-to-member-function?
  (renamed the macro to all-caps)
• [33.7] How do I create and use an array of pointer-to-member-function?
  (renamed the macro to all-caps)
• [35.12] Why can't I separate the definition of my templates class from its declaration and put it inside a .cpp file?
  (added the caveat at the beginning; wordsmithed throughout)
• [37.4] Where can I get help on how to use STL?
  (added Rogue Wave's STL Guide thanks to Richard van Wegen)
• [37.8] Why is my executable so large?
  (added the paragraph on debugging thanks to Richard van Wegen; rewrote the second paragraph)
• [38.1] Where can I download a free C++ compiler?
  (added several new links thanks to Thomas Tutone)
• [39.1] How do I convert a value (a number, for example) to a std::string?
  (fixed a typo in the last paragraph thanks to Alex Rutchka, rewrote the code examples to use exceptions, and moved it from the I/O section)
• [39.2] How do I convert a std::string to a number?
  (rewrote the code examples to use exceptions, added the failIfLeftoverChars, and moved it from the I/O section)
• [39.4] What should be done with macros that contain if?
  (reworded in various spots)
• [39.5] What should be done with macros that have multiple lines?
  (reworded)