C++ std::bind用法详解

template< class F, class... Args >
/*unspecified*/ bind( F&& f, Args&&... args );
 
template< class R, class F, class... Args >
/*unspecified*/ bind( F&& f, Args&&... args );

#include <iostream>
#include <functional>
using namespace std;
 
int TestFunc(int a, char c, float f)
{
    cout << a << endl;
    cout << c << endl;
    cout << f << endl;
 
    return a;
}
 
int main()
{
    auto bindFunc1 = bind(TestFunc, std::placeholders::_1, 'A', 100.1);
    bindFunc1(10); //等于TestFunc(10,'A', 100.1)
 
    cout << "=================================\n";
 
    auto bindFunc2 = bind(TestFunc, std::placeholders::_2, std::placeholders::_1, 100.1);
    bindFunc2('B', 10); //等于TestFunc(10,'B', 100.1)
 
    cout << "=================================\n";
 
    auto bindFunc3 = bind(TestFunc, std::placeholders::_2, std::placeholders::_3, std::placeholders::_1);
    bindFunc3(100.1, 30, 'C'); //等于TestFunc(30,'C', 100.1)
 
    return 0;
}

auto bindFunc3 = bind(TestFunc, std::placeholders::_2, std::placeholders::_3, std::placeholders::_1);
 
bindFunc3(100.1, 30, 'C');

#include <random>
#include <iostream>
#include <memory>
#include <functional>
 
void f(int n1, int n2, int n3, const int& n4, int n5)
{
	std::cout << n1 << ' ' << n2 << ' ' << n3 << ' ' << n4 << ' ' << n5 << '\n';
}
 
int g(int n1)
{
	return n1;
}
 
struct Foo {
	void print_sum(int n1, int n2)
	{
		std::cout << n1 + n2 << '\n';
	}
	int data = 10;
};
 
int main()
{
	using namespace std::placeholders;  // for _1, _2, _3...
 
	// demonstrates argument reordering and pass-by-reference
	int n = 7;
	// (_1 and _2 are from std::placeholders, and represent future
	// arguments that will be passed to f1)
 
	auto f1 = std::bind(f, _2, 42, _1, std::cref(n), n);
	n = 10;
	f1(1, 2, 1001); // 1 is bound by _1, 2 is bound by _2, 1001 is unused
					// makes a call to f(2, 42, 1, n, 7)
 
	// nested bind subexpressions share the placeholders
	auto f2 = std::bind(f, _3, std::bind(g, _3), _3, 4, 5);
	f2(10, 11, 12); // makes a call to f(12, g(12), 12, 4, 5);
 
	// bind to a pointer to member function
	Foo foo;
	auto f3 = std::bind(&Foo::print_sum, &foo, 95, _1);
	f3(5);
 
	// bind to a pointer to data member
	auto f4 = std::bind(&Foo::data, _1);
	std::cout << f4(foo) << '\n';
 
	std::cout << f4(std::make_shared<Foo>(foo)) << '\n'
		<< f4(std::make_unique<Foo>(foo)) << '\n';
 
        return 0;
}