STL：算法

STL：算法

参考文献《大道至简：C++STL》

• for_each()、count()、min_element()/max_element()

#include <iostream>
#include <vector>
#include <deque>
#include <list>
#include <algorithm>

#ifndef __print__
    #define __print__(x) {std::cout << x << " ";}
#endif

#ifndef newline
    #define newline() {std::cout << std::endl;}
#endif

using namespace std;

template <typename T> void _pow(T& t) {t *= t;}

template <typename T> void print(const T& t){__print__(t);}

class SUM
{
private:
    long total;
public:
    SUM():total(0){}
    void operator()(int val)
    {
        total += val;
    }
    operator double()
    {
        return static_cast<double>(total);
    }
};

bool is_even(const int& x){return x % 2 == 0;}
template <typename T> bool abs_val(const T& t1, const T& t2){return abs(t1) < abs(t2);};

int main()
{

/*for_each()*/

    vector<int> vint = {1, 3, 5, 7};
    for_each(vint.begin(), vint.end(), print<int>);
    newline();
    for_each(vint.begin(), vint.end(), _pow<int>);
    for_each(vint.begin(), vint.end(), print<int>);
    newline();
    double sum = for_each(vint.begin(), vint.end(), SUM());
    print(sum);
    newline();

/*count()*/

    deque<int> dint = {2, 5, 4, 1, 8, 3, 6};
    for_each(dint.begin(), dint.end(), print<int>);
    newline();
    print(count(dint.begin(), dint.end(), 4));
    print(count_if(dint.begin(), dint.end(), bind2nd(greater<int>(), 3)));
    print(count_if(dint.begin(), dint.end(), is_even));
    newline();

/*min_element/max_element*/

    list<int> lint = {-1, 4, 6, -12, 9};
    print(*min_element(lint.begin(), lint.end()));
    newline();
    print(*max_element(lint.begin(), lint.end()));
    newline();
    print(*min_element(lint.begin(), lint.end(), abs_val<int>));    //-1
    newline();
    print(*max_element(lint.begin(), lint.end(), abs_val<int>));    //-12
    newline();

    return 0;
}