What does __cdecl *_PVFV stands for?

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Hi Friends,
I was actually lerning some new stuffs in Visual C++ and I come across a code in one of the file.

C++

typedef void (__cdecl *_PVFV)(void);

I understand that the code is MSVC++ specific and I have to look at some good book but for the time being, can you please provide me with a satisfactory answer about what the _PVFV is? I also have looked at _PIFV... Please help me regarding this.... I will be vey much thank ful to you.

With Regards
Tushar Srivastava

Posted 7-Sep-13 23:16pm

Er. Tushar Srivastava

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pasztorpisti 8-Sep-13 5:54am

Learning C by reading the runtime library (that has hell ugly and often platform specific source code) is not a good idea. Actually this piece of code is not MSVC specific at all.

2 solutions

Solution 2

Function pointer typedefs may look a bit 'esoteric'. You may find interesting this Stack Overflow question: "Understanding typedefs for function pointers in C: Examples, hints and tips, please"[^]

Posted 8-Sep-13 23:20pm

CPallini

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pasztorpisti 9-Sep-13 5:32am

+5 Exactly. One of the cases where the typedef must be read starting from the middle.

CPallini 9-Sep-13 5:36am

Thank you.

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pasztorpisti · Accepted Answer · 2013-09-07T23:53:00

Solution 1

This is a function pointer declaration. typedef void (*_PVFV)(void); defines _PVFV as a function pointer type. The __cdecl keyword is there to define the calling convention of the function to use C calling convention[^].

Posted 7-Sep-13 23:53pm

pasztorpisti

Updated 8-Sep-13 22:47pm

v2

Comments

H.Brydon 8-Sep-13 17:24pm

(+5)

Your url seems to be truncated. Perhaps you meant http://en.wikipedia.org/wiki/Calling_convention (?)

Another link that might be better is http://en.wikipedia.org/wiki/X86_calling_conventions

Also:
http://msdn.microsoft.com/en-us/library/zxk0tw93%28vs.71%29.aspx
http://msdn.microsoft.com/en-us/library/984x0h58%28v=vs.71%29.aspx

pasztorpisti 9-Sep-13 4:48am

Thank you! The link was indeed truncated but your additional links are better anyway. A virtual +5. :-)

CPallini 9-Sep-13 5:10am

5.

pasztorpisti 9-Sep-13 5:31am

Thank you!

Er. Tushar Srivastava 10-Sep-13 6:53am

My Question actually was, What is _PVFV and _PIFV :) Thank you for the reply by the way :)

pasztorpisti 10-Sep-13 7:12am

_PVFV: I'm lazy to browse the sources but I remember one important use of _PVFV (there may be other uses too). When you declare complex global variables (for example a non-POD class variables with constuructor and/or destructor) then the compiler generates 1 or two _PVFV compatible functions for your global variable initialization. Then the compiler automatically "declares/defines" a _PVFV func pointer variable in a segment that is specially named, the name must fall between ".CRT$XCA" and ".CRT$XCZ". This function pointer variable will point to the initializer _PVFV function that calls the constructor of the global variable and then calls atexit() with the destructor _PVFV function (if the global var has destructor code). Since the linker assemble executables by alphabetically sorting segments these compiler-defined init-function pointer variables will be put to a continuous memory area (even if the pointers come from totally different object files) in the executable and the crt code will be able to iterate through this array to call all of them before executing the main() of your program. During initialization the init _PVFV methods install the required atexit() handlers too (that will call the destructor _PVFV functions when your return from your main() or if you call exit()) for your global vars as I mentioned previously. To see this code in action take a look at the MiniCRT "library" in one of my tips: http://www.codeproject.com/script/Articles/ViewDownloads.aspx?aid=430684

_PIFV and its friends: continue reading the crt sources if you are so interested.