Minimal runnable example
main.cpp
#include <cassert>
class C {
public:
int i;
C(int i) : i(i) {}
int m(int j) { return this->i + j; }
};
int main() {
// Get a method pointer.
int (C::*p)(int) = &C::m;
// Create a test object.
C c(1);
C *cp = &c;
// Operator .*
assert((c.*p)(2) == 3);
// Operator ->*
assert((cp->*p)(2) == 3);
}
Compile and run:
g++ -ggdb3 -O0 -std=c++11 -Wall -Wextra -pedantic -o main.out main.cpp
./main.out
Tested in Ubuntu 18.04.
You cannot change the order of the parenthesis or omit them. The following do not work:
c.*p(2)
c.*(p)(2)
GCC 9.2 would fail with:
main.cpp: In function ‘int main()’:
main.cpp:19:18: error: must use ‘.*’ or ‘->*’ to call pointer-to-member function in ‘p (...)’, e.g. ‘(... ->* p) (...)’
19 | assert(c.*p(2) == 3);
|
C++11 standard
.*
and ->*
are a single operators introduced in C++ for this purpose, and not present in C.
.*
and ->*
.