传入参数

要传入参数给global function ,需要使用 ptr_fun() 这个 function adapter 将global function 转成function object , 然后再用bind2nd() 将参数bind成一个function object。（这句话好拗口）

void fun(int i, const char* str)
{cout<<str<<i<<endl;
}int main()
{int a[] = { 1, 2, 3, 4};vector<int> v(a, a+sizeof(a)/sizeof(int));for_each(v.begin(), v.end(), bind2nd(ptr_fun(fun), "Element:"));
}

#include <iostream>
#include <vector>template<class T>
struct plus2{void operator()(T& x){x += 2;}
};//template <class T>
void plus3_fun(int& x){x += 3;
//    std::cout << x << " ";
}void fun(int i,const char* str){std::cout << str << "->" << i << std::endl;
}int main(){
//    int ia[] = {22,30,20,34,45,64,34,56,75,34};
//    std::vector<int>iv(ia,ia+(sizeof (ia) / sizeof (int)));
//    for (int i : iv) {
//        std::cout << i << ' ';
//    }
//    std::cout << std::endl;
//    std::cout << iv.size() << ' ';
//    std::cout << std::endl;
//std::for_each(iv.begin(),iv.end(),plus2<int>());
//    std::for_each(iv.begin(),iv.end(), std::bind2nd(std::ptr_fun(fun),"Hello world"));
//    for (int i : iv) {
//        std::cout << i << ' ';
//    }int ia[] = {1,2,100,200};std::vector<int>arr(ia,ia+(sizeof (ia)/sizeof (int)));//移除所有小于100的元素//bind2nd(判断条件,标准)  判断条件 标准//bind1nd(判断条件,标准)  标准 判断条件/** std::bind1nd(std::less<int>(),100))   100 < x* std::bind2nd(std::less<int>(),100))   x < 100*/
//    arr.erase(std::remove_if(arr.begin(),arr.end(),std::bind2nd(std::less<int>(),100)),arr.end()); //100 200
//    arr.erase(std::remove_if(arr.begin(),arr.end(),std::bind1st(std::greater<int>(),100)),arr.end());//    arr.erase(std::remove_if(arr.begin(),arr.end(),std::bind2nd(std::greater<int>(),100)),arr.end());
//    arr.erase(std::remove_if(arr.begin(),arr.end(),std::bind1st(std::less<int>(),100)),arr.end()); //1 2 100//删除小于等于100的元素arr.erase(std::remove_if(arr.begin(),arr.end(),std::not1(std::bind2nd(std::greater<int>(),100))),arr.end());for(auto i : arr){std::cout << i << " ";}
}

ptr_fun

C++11弃用被更通用的std::function 和 std::ref替代

#include <iostream>
#include <vector>
#include <functional>
#include <algorithm>bool isvowel(char c){return std::string("aeiouAEIOU").find(c) != std::string::npos;
}int main(){std::string s = "Hello world!";std::copy_if(s.begin(),s.end(),std::ostreambuf_iterator<char>(std::cout),std::not1(std::ptr_fun(isvowel)));
}//Hll wrld!

std::function函数

std::function - cppreference.com

#include <iostream>
#include <vector>
#include <functional>
#include <algorithm>struct Foo{Foo(int num):num_(num){};void print_add(int i)const {std::cout << num_ + i << std::endl;}int num_;
};
void print_num(int i){std::cout << i << '\n';
}
struct print_Num{void operator()(int i){std::cout << i << '\n';}
};int main(){//store a free functionstd::function<void(int)>f_display = print_num;f_display(-9);//strore a lambdastd::function<void()> f_display_42 = [](){ print_num(43);};f_display_42();//store the result of a call to std::bindstd::function<void()>f_display_31337 = std::bind(print_num,31337);f_display_31337();//store a call to a member functionstd::function<void(const Foo&,int)>f_add_display = &Foo::print_add;const Foo foo(300000);f_add_display(foo,1);//store a call to a member function and objectusing std::placeholders::_1;std::function<void(int)>f_add_display2 = std::bind(&Foo::print_add,foo,_1);f_add_display2(2);//store a call to a member function and object ptrstd::function<void(int)>f_add_display3 = std::bind(&Foo::print_add,&foo,_1);f_add_display3(3);//store a call to a function objectstd::function<void(int)>f_display_obj = print_Num();f_display_obj(18);
}

参考链接