c++函数对象

#include <iostream>
#include <vector>
#include <algorithm>


// 定义一个模板函数
template<class TF>
void general( std::vector<int>::iterator begin,
              std::vector<int>::iterator end,
              TF f ) {
    std::vector<int>::iterator itr;
    for(itr = begin; itr != end; itr++) {
        f(*itr);
    }
}

void add( int &rr ) {
    ++rr;
}
void output(const int &rr) {
    std::cout << rr << " ";
}

void test01() {
    std::vector<int> v;
    v.push_back(10);
    v.push_back(3);
    v.push_back(4);
    general(v.begin(), v.end(), add);
    general(v.begin(), v.end(), output);
    std::cout << std::endl;

    std::cout << "系统函数 for_each : " << std::endl;
    for_each(v.begin(), v.end(), add);
    for_each(v.begin(), v.end(), output);
    std::cout << std::endl;

    std::cout << "test01 end ......" << std::endl;
}

template<class T1, class T2>
void merge(T1 a[], T1 b[], T1 c[], int size, T2 f) {
    for (int i = 0; i < size; ++i) {
        c[i] = f(a[i], b[i]);
    }
}


// 函数对象的使用
void test02() {
    std::string s1[3] = {"aa", "bb", "cc"};
    std::string s2[3] = {"xx", "yy", "zz"};
    std::string s3[3];

    merge(s1, s2, s3, 3, std::plus<std::string>()); // 包 functional
    for (int i = 0; i < 3; ++i) {
        std::cout << s3[i] << std::endl;
    }
    std::cout << "s2 length ??? : " << s2->length() << std::endl;
    std::cout << "test02 end ......" << std::endl;
}

int main() {
    test01();
    test02();

    return 0;
}