What does "typedef void (*Something)()" mean

c++ typedef static-members void-pointers
DogDog picture DogDog · Oct 20, 2010 · Viewed 49.4k times · Source

I am trying to understand what this means, the code I am looking at has

in .h

typedef void (*MCB)();
static MCB     m_process;

in .C

MCB Modes::m_process = NULL;

And sometimes when I do

m_process();

I get segmentations fault, it's probably because the memory was freed, how can I debug when it gets freed?

I hope my questions are clear.

Answer

Jonathan Leffler picture Jonathan Leffler · Oct 20, 2010

It defines a pointer-to-function type. The functions return void, and the argument list is unspecified because the question is (currently, but possibly erroneously) tagged C; if it were tagged C++, then the function would take no arguments at all. To make it a function that takes no arguments (in C), you'd use:

typedef void (*MCB)(void);

This is one of the areas where there is a significant difference between C, which does not - yet - require all functions to be prototyped before being defined or used, and C++, which does.

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