1.Boost：bind
#include <iostream>
#include <boost/bind.hpp>
using namespace std;
using namespace boost;
int f(int a, int b = 12)
{
return a + b;
}
int g(int a, int b, int c)
{
return a + b + c;
}
int main(int argc, char *argv[])
{
//通过下面方法调用等价于f(1,2);
cout << "bind(f, 1, 2)() = " <<bind(f, 1, 2)() << endl;
//同样能够绑定部分参数，例如：下方表示第二个参数传递的是15
cout << "bind(f, 12, _1)(15) = " <<bind(f, 12, _1)(15) << endl;
//用两个占位符
cout << "bind(f, _1, _2)(1, 3) = " <<bind(f, _1, _2)(1, 3) << endl;
cout << "----------" << endl;
//引入参数调用的方式
int i = 5;
cout << "bind(f, i, _1)(1) = " << bind(f, i, _1)(1) << endl;
cout << "----------" << endl;
//等价于g(1,2,3)
cout << "bind(g, 1, 2, 3)() = " <<bind(g, 1, 2, 3)()<< endl;
//用三个占位符的情况
cout << "bind(g,_1,_2,_3)(2,3,4) = " << bind(g,_1,_2,_3)(2,3,4) << endl;
cin.get();
return 0;
}
运行结果：
2.boost案例1
#include <iostream>
#include <string>
#include <boost/bind.hpp>
#include <vector>
#include <algorithm>
#include <functional>
using namespace std;
using namespace boost;
//绑定函数的默认值，继承二进制函数类的所有内容
class add :public std::binary_function<int, int, void>
{
public:
void operator()(int i, int j) const
{
std::cout << i + j << std::endl;
}
};
void add(int i, int j)
{
std::cout << i + j << std::endl;
}
void main()
{
vector<int> myv;
myv.push_back(11);
myv.push_back(23);
myv.push_back(34);
for_each(myv.begin(), myv.end(), bind(add, 13, _1));
cin.get();
}
运行结果：
3bind并不仅仅限于方法，下面的例子是绑定结构体的情况。
#include <iostream>
#include <boost/bind.hpp>
#include <algorithm>
#include <cassert>
using namespace std;
using namespace boost;
struct F
{
int operator()(int a, int b){ return a - b; };
bool operator()(long a, long b){ return a == b; };
};
struct F2
{
int s;
typedef void result_type;
void operator()(int x)
{
s += x;
std::cout << "x = " << x <<" s = "<< s << std::endl;
}
};
int main(int argc,char *argv[])
{
F f;
int x = 104;
//通过：bind<R>(f, ...) 这种语法，但是
cout << "bind<int>(f, _1, _2)(10,5) = " <<bind<int>(f, _1, _2)(10,5) << endl;
cout << "---------" << endl;
//通过：boost::bind(boost::type<R>(),f,_1,_2)(x,y);的方式进行绑定
cout << "boost::bind(boost::type<int>(), f, _1, 3)(8)= "<<boost::bind(boost::type<int>(), f, _1, 3)(8) << endl;
F2 f2 = { 0 };
int a[] = { 1, 2, 3 };
cout << "---------" << endl;
//for_each是#include <algorithm>中的
for_each(a, a + 3, bind(std::ref(f2), _1));
//下面的是#include <cassert>头文件中的
//assert(f2.s == 6);
cin.get();
return 0;
}
运行结果：
