// bind example
#include <iostream> // std::cout
#include <functional> // std::bind
// a function: (also works with function object: std::divides<double> my_divide;)
double my_divide (double x, double y) {return x/y;}
struct MyPair {
double a,b;
double multiply() {return a*b;}
};
int main () {
using namespace std::placeholders; // adds visibility of _1, _2, _3,...
// binding functions:
auto fn_five = std::bind (my_divide,10,2); // returns 10/2
std::cout << fn_five() << '\n'; // 5
auto fn_half = std::bind (my_divide,_1,2); // returns x/2
std::cout << fn_half(10) << '\n'; // 5
auto fn_invert = std::bind (my_divide,_2,_1); // returns y/x
std::cout << fn_invert(10,2) << '\n'; // 0.2
auto fn_rounding = std::bind<int> (my_divide,_1,_2); // returns int(x/y)
std::cout << fn_rounding(10,3) << '\n'; // 3
MyPair ten_two {10,2};
// binding members:
auto bound_member_fn = std::bind (&MyPair::multiply,_1); // returns x.multiply()
std::cout << bound_member_fn(ten_two) << '\n'; // 20
auto bound_member_data = std::bind (&MyPair::a,ten_two); // returns ten_two.a
std::cout << bound_member_data() << '\n'; // 10
return 0;
}
Ly8gYmluZCBleGFtcGxlCiNpbmNsdWRlIDxpb3N0cmVhbT4gICAgIC8vIHN0ZDo6Y291dAojaW5jbHVkZSA8ZnVuY3Rpb25hbD4gICAvLyBzdGQ6OmJpbmQKCi8vIGEgZnVuY3Rpb246IChhbHNvIHdvcmtzIHdpdGggZnVuY3Rpb24gb2JqZWN0OiBzdGQ6OmRpdmlkZXM8ZG91YmxlPiBteV9kaXZpZGU7KQpkb3VibGUgbXlfZGl2aWRlIChkb3VibGUgeCwgZG91YmxlIHkpIHtyZXR1cm4geC95O30KCnN0cnVjdCBNeVBhaXIgewogIGRvdWJsZSBhLGI7CiAgZG91YmxlIG11bHRpcGx5KCkge3JldHVybiBhKmI7fQp9OwoKaW50IG1haW4gKCkgewogIHVzaW5nIG5hbWVzcGFjZSBzdGQ6OnBsYWNlaG9sZGVyczsgICAgLy8gYWRkcyB2aXNpYmlsaXR5IG9mIF8xLCBfMiwgXzMsLi4uCgogIC8vIGJpbmRpbmcgZnVuY3Rpb25zOgogIGF1dG8gZm5fZml2ZSA9IHN0ZDo6YmluZCAobXlfZGl2aWRlLDEwLDIpOyAgICAgICAgICAgICAgIC8vIHJldHVybnMgMTAvMgogIHN0ZDo6Y291dCA8PCBmbl9maXZlKCkgPDwgJ1xuJzsgICAgICAgICAgICAgICAgICAgICAgICAgIC8vIDUKCiAgYXV0byBmbl9oYWxmID0gc3RkOjpiaW5kIChteV9kaXZpZGUsXzEsMik7ICAgICAgICAgICAgICAgLy8gcmV0dXJucyB4LzIKICBzdGQ6OmNvdXQgPDwgZm5faGFsZigxMCkgPDwgJ1xuJzsgICAgICAgICAgICAgICAgICAgICAgICAvLyA1CgogIGF1dG8gZm5faW52ZXJ0ID0gc3RkOjpiaW5kIChteV9kaXZpZGUsXzIsXzEpOyAgICAgICAgICAgIC8vIHJldHVybnMgeS94CiAgc3RkOjpjb3V0IDw8IGZuX2ludmVydCgxMCwyKSA8PCAnXG4nOyAgICAgICAgICAgICAgICAgICAgLy8gMC4yCgogIGF1dG8gZm5fcm91bmRpbmcgPSBzdGQ6OmJpbmQ8aW50PiAobXlfZGl2aWRlLF8xLF8yKTsgICAgIC8vIHJldHVybnMgaW50KHgveSkKICBzdGQ6OmNvdXQgPDwgZm5fcm91bmRpbmcoMTAsMykgPDwgJ1xuJzsgICAgICAgICAgICAgICAgICAvLyAzCgogIE15UGFpciB0ZW5fdHdvIHsxMCwyfTsKCiAgLy8gYmluZGluZyBtZW1iZXJzOgogIGF1dG8gYm91bmRfbWVtYmVyX2ZuID0gc3RkOjpiaW5kICgmTXlQYWlyOjptdWx0aXBseSxfMSk7IC8vIHJldHVybnMgeC5tdWx0aXBseSgpCiAgc3RkOjpjb3V0IDw8IGJvdW5kX21lbWJlcl9mbih0ZW5fdHdvKSA8PCAnXG4nOyAgICAgICAgICAgLy8gMjAKCiAgYXV0byBib3VuZF9tZW1iZXJfZGF0YSA9IHN0ZDo6YmluZCAoJk15UGFpcjo6YSx0ZW5fdHdvKTsgLy8gcmV0dXJucyB0ZW5fdHdvLmEKICBzdGQ6OmNvdXQgPDwgYm91bmRfbWVtYmVyX2RhdGEoKSA8PCAnXG4nOyAgICAgICAgICAgICAgICAvLyAxMAoKICByZXR1cm4gMDsKfQ==