15、stl 常用算法

#include <iostream>
using namespace std;

#include "string"
#include <vector>
#include <list>
#include "set"
#include <algorithm>
#include "functional"
#include "iterator"  //输出流迭代器的头文件

void printV(vector<int> &v)
{
    for (vector<int>::iterator it=v.begin(); it!=v.end(); it++)
    {
        cout << *it << " ";
    }
}

void printList(list<int> &v)
{
    for (list<int>::iterator it=v.begin(); it!=v.end(); it++)
    {
        cout << *it << " ";
    }
}

void showElem(int &n)
{
    cout << n << " ";
}

class CMyShow
{
public:
    CMyShow()
    {
        num = 0;
    }
    void operator()(int &n)
    {
        num ++;
        cout << n << " ";
    }
    void printNum()
    {
        cout << "num:" << num << endl;
    }
protected:
private:
    int num;
};

void main41_foreach()
{
    vector<int> v1;
    v1.push_back(1);
    v1.push_back(3);
    v1.push_back(5);

    printV(v1);
    cout << endl;

    /*
    template<class _InIt,
    class _Fn1> inline
        _Fn1 for_each(_InIt _First, _InIt _Last, _Fn1 _Func)
    {   // perform function for each element
        _DEBUG_RANGE(_First, _Last);
        _DEBUG_POINTER(_Func);
        return (_For_each(_Unchecked(_First), _Unchecked(_Last), _Func));
    } */

    //函数对象 回调函数入口地址
    for_each(v1.begin(), v1.end(), showElem);
    cout << endl;

    for_each(v1.begin(), v1.end(), CMyShow());
    cout << endl;

     CMyShow mya;
     CMyShow my1 = for_each(v1.begin(), v1.end(),mya); //给my1初始化
     mya.printNum();  //ma1和my1 是两个不同的对象
     my1.printNum();

     my1 = for_each(v1.begin(), v1.end(),mya);  //给my1赋值
     my1.printNum();
}


int  increase(int i)
{
    return i+100;
}

void main42_transform()
{
    vector<int> v1;
    v1.push_back(1);
    v1.push_back(3);
    v1.push_back(5);

    printV(v1);
    cout << endl;

    //transform 使用回调函数
    transform(v1.begin(), v1.end(), v1.begin(),  increase ); 
    printV(v1);
    cout << endl;

    //transform 使用 预定义的函数对象
    transform(v1.begin(), v1.end(), v1.begin(),  negate<int>() ); 
    printV(v1);
    cout << endl;

    //transform 使用 函数适配器 和函数对象
    list<int> mylist;
    mylist.resize( v1.size() );

    transform(v1.begin(), v1.end(), mylist.begin(),  bind2nd( multiplies<int>(), 10 ) ); 
    printList(mylist);
    cout << endl;

    //transform 也可以把运算结果 直接输出到屏幕
    transform(v1.begin(), v1.end(), ostream_iterator<int>(cout, " " ), negate<int>() );
    cout << endl;
}


//一般情况下：for_each所使用的函数对象，参数是引用，没有返回值
//transform所使用的函数对象，参数一般不使用引用，而是还有返回值
int showElem2(int n)
{
    cout << n << " ";
    return n;
}

void main43_transform_pk_foreach()
{
    vector<int> v1;
    v1.push_back(1);
    v1.push_back(3);
    v1.push_back(5);

    vector<int> v2 = v1;

    for_each(v1.begin(), v1.end(), showElem);


    //transform 对 函数对象的要求
    /*
c:\program files\microsoft visual studio 10.0\vc\include\algorithm(1119): 
    参见对正在编译的函数 模板 实例化
        “_OutIt std::_Transform1<int*,_OutIt,
        void(__cdecl *)(int &)>(_InIt,_InIt,_OutIt,_Fn1,
        std::tr1::true_type)”的引用
1>          with
1>          [
1>              _OutIt=std::_Vector_iterator<std::_Vector_val<int,std::allocator<int>>>,
1>              _InIt=int *,
1>              _Fn1=void (__cdecl *)(int &)
1>          ]
    */

    /*
    template<class _InIt,
    class _OutIt,
    class _Fn1> inline
        _OutIt _Transform(_InIt _First, _InIt _Last,
        _OutIt _Dest, _Fn1 _Func)
    {   // transform [_First, _Last) with _Func
        for (; _First != _Last; ++_First, ++_Dest)
            *_Dest = _Func(*_First);  //解释了 为什么 要有返回值
        return (_Dest);
    }
    */
    transform(v2.begin(), v2.end(), v2.begin(), showElem2);
}

void main()
{
    //main41_foreach();
    //main42_transform();
    // main43_transform_pk_foreach();
    cout<<"hello..."<<endl;
    system("pause");
    return ;
}