printf(“%p”) and casting to (void *)

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The %p conversion specifier requires an argument of type void *. If you don’t pass an argument of type void *, the function call invokes undefined behavior.

From the C Standard (C11, 7.21.6.1p8 Formatted input/output functions):

“p – The argument shall be a pointer to void.”

Pointer types in C are not required to have the same size or the same representation.

An example of an implementation with different pointer types representation is Cray PVP where the representation of pointer types is 64-bit for void * and char * but 32-bit for the other pointer types.

See “Cray C/C++ Reference Manual”, Table 3. in “9.1.2.2” http://docs.cray.com/books/004-2179-003/004-2179-003-manual.pdf

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