第15周阅读程序5

#include <iterator>
#include <algorithm>
#include <functional>
#include <iostream>
#include <vector>
using namespace std;
class Angle
{
    int degrees;
public:
    Angle(int deg) : degrees(deg) {}
    int mul(int times)
    {
        return degrees *= times;
    }
};
int main()
{
    int x[] = {1, 2, 4, 5, 8};
    vector<Angle> va;
    for(int i =10; i <= 50; i += 10)
        va.push_back(Angle(i));
    transform(va.begin(), va.end(), x, ostream_iterator<int>(cout , "  "), mem_fun_ref(&Angle::mul));
    cout << endl;
    return 0;
}

运行结果：

过程分析：

STL 标准库中的函数适配器辅助函数说明

适配器辅助函数                                                           功能说明

ptr_fun                                                           辅助构造一般函数指针的pointer_to_unary_function或pointer_to_binary_function适配器实例

mem_fun                                                       辅助构造mem_fun_t等成员函数适配器实例，返回一元或二元函数对象

mem_fun_ref                                                辅助构造mem_fun_ref_t等成员函数适配器实例，返回一元或二元函数对象