Language
C++
Compiler
clang 15.0.7
Options
Warnings
Boost 1.80.0
C++2b(GNU)
no pedantic
$ clang++ prog.cc -Wall -Wextra -I/opt/wandbox/boost-1.80.0-clang-15.0.7/include -std=gnu++2b ***** free function demo *****
int square_num(int i)
{
return i*i;
}
function<int(int)> {square_num}(-9) = 81
function<int(int)> {bind(square_num,placeholders::_1)}(9) = 81
function<int()> {bind(square_num,9)}() = 81
***** struct demo *****
struct Foo
{
Foo(int num) : num_(num) {}
void print_add(int i) const { cout << num_ + i << endl; }
int num_;
} foo {200};
function<void(const Foo&, int)>{&Foo::print_add}(foo, 100) = 300
function<int(Foo const&)> {&Foo::num_}(foo) = 200
function<void(int)> {bind(&Foo::print_add, foo, placeholders::_1)}(2) = 202
function<void(int)> {bind(&Foo::print_add, &foo, placeholders::_1)}(3) = 203
***** functor demo *****
function<int(int)>{negate<int>()}(18) = -18
***** lambda expression demo *****
function<void(int)> {[](int i) { cout << i << endl; }}(42) = 42
auto factorial = [](int n)
{
// store a lambda object to emulate "recursive lambda"; aware of extra overhead
function<int(int)> fac = [&](int n)
{
cout << n << ' ';
return (n < 2) ? 1 : fac(n - 1);
};
// note that "auto fac = [&](int n) {...};" does not work in recursive calls
fac(n);
};
factorial(5)! = 5 4 3 2 1 Exit Code:
0