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437. Formatted output of function pointers is confusing

Section: [ostream.inserters.arithmetic] Status: NAD Submitter: Ivan Godard Opened: 2003-10-24 Last modified: 2016-12-23

Priority: Not Prioritized

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void f(int) {}
void(*g)(int) = f;
cout << g;

(with the expected #include and usings), the value printed is a rather surprising "true". Rather useless too.

The standard defines:

ostream& operator<<(ostream&, void*);

which picks up all data pointers and prints their hex value, but does not pick up function pointers because there is no default conversion from function pointer to void*. Absent that, we fall back to legacy conversions from C and the function pointer is converted to bool.

There should be an analogous inserter that prints the address of a function pointer.

Proposed resolution:


This is indeed a wart, but there is no good way to solve it. C doesn't provide a portable way of outputting the address of a function point either.