How Do I Print Function Pointers in C Using `cout` and `printf`?

Printing Function Pointers with cout and printf

In C , function pointers can be printed using cout or printf, but with different behavior depending on the format specifier used.

cout Operator

By default, cout treats function pointers as boolean values and prints 1 for non-null pointers and 0 for null pointers. To print the actual address, it must be explicitly cast to void*:

cout << (void *)pf;

printf Function

When using printf with the %p format specifier, function pointers are treated as pointers and their addresses are printed in hexadecimal:

printf("%p", pf);

Function Pointers as Booleans

Function pointers are indeed treated as booleans in C . This is due to the boolean conversion rule that allows pointers to be cast to bool, where a non-null pointer evaluates to true and a null pointer to false. This behavior can be unexpected if not taken into consideration.

Member Function Pointers

Printing member function pointers is more complex as they are not simple pointers. However, it is possible to print the address of the member function using a trick:

cout << (void *)(*(int **)&pf);

This takes advantage of the fact that the address of the member function is stored in the function pointer's second element, and casts it to void*.

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