CODEWITHSUNDEEP
cmemoryruntimec99
sudeepdino008
sudeepdino008

Reputation: 3364

How is a C function pointer laid out in memory

There's some information about how struct is laid out in memory in a C process. I wanted to know how a function pointer is laid out in memory. e.g.

void (*fun_ptr)(int)

Upvotes: 0

Views: 88

Answers (1)

John Bode
John Bode

Reputation: 123578

This is entirely a function of the underlying platform. C does not specify the representation of any pointer type, only what its behavior needs to be.

C does specify that object and function pointers are not interchangeable; a void * can be converted to any object pointer type and vice-versa, and a function pointer type can be converted to any other function pointer type, but converting between object and function pointers may not be allowed (gcc with the -pedantic flag will yak if you try to convert a function pointer to void * or vice-versa).

Pointers may have a simple flat integer representation, or they may be a structured representation like a page number and an offset, or they may be something else. Pointers to different types don't have to have the same size and representation - e.g., a char * doesn't have to have the same representation as an int *, which doesn't have to have the same representation as a struct foo *, etc.

But again, it depends entirely on the platform.

Upvotes: 2

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