C++ STL function object学习

C++ STL函数对象

cfunctionobject2020101101.cpp

//cfunctionobject2020101101.cpp
#include <iostream>
#include <list>
#include <algorithm>
#include <iterator>

#include "print.hpp"

using namespace std;

class IntSequence
{
private:
    int value;
public:
    IntSequence(int initialValue):value(initialValue) 
    {}

    //
    int operator() ()
    {
        return ++value;
    }
};



int main()
{
    list<int> coll;

    //insert values from 1 to 9
    generate_n(back_inserter(coll),
        9,
        IntSequence(1));
    
    PRINT_ELEMENTS(coll);

    //replace seconds to last element but one with values starting at 42
    generate(next(coll.begin()),
        prev(coll.end()),
        IntSequence(42));

    PRINT_ELEMENTS(coll);
}

print.hpp

//print.hpp
#include <iostream>
#include <string>

template <typename T>
inline void PRINT_ELEMENTS(const T& coll, const std::string& optstr = "")
{
    std::cout << optstr;
    for (const auto& elem : coll)
    {
        std::cout << elem << "  ";
    }
    std::cout << std::endl;
}

运行结果

2 3 4 5 6 7 8 9 10
2 43 44 45 46 47 48 49 10