《C++标准程序库》读书笔记（四）

#include <iostream>
#include <list>
#include <algorithm>
using namespace std;

int main()
{
    list<int> coll;
    list<int>::iterator pos25,pos35,pos;
    for(int i=20;i<=40;++i)
        coll.push_back(i);
    pos25 = find(coll.begin(),coll.end(),25);
    pos35 = find(coll.begin(),pos25,35);
    if(pos35!=pos25)
    {//pos35在pos25前
        pos = find(coll.begin(),pos25,30);
    }
    else
    {//pos25在pos35前
        pos = find(pos25,coll.end(),30);
    }
    cout<<"num: "<<*pos<<endl;
    system("pause");
    return 0;
}

使用仿函数

#include <functional>
/* class for the compose_f_gx_hx adapter*/
template <class OP1, class OP2, class OP3>
class compose_f_gx_hx_t
: public std::unary_function<typename OP2::argument_type,
                              typename OP1::result_type>
{
  private:
    OP1 op1;    // process: op1(op2(x),op3(x))
    OP2 op2;
    OP3 op3;
  public:
    // constructor
    compose_f_gx_hx_t (const OP1& o1, const OP2& o2, const OP3& o3)
     : op1(o1), op2(o2), op3(o3) {
    }
    // function call
    typename OP1::result_type
operator()(const typename OP2::argument_type& x) const
{
        return op1(op2(x),op3(x));
    }
};
/* convenience function for the compose_f_gx_hx adapter*/
template <class OP1, class OP2, class OP3>
inline compose_f_gx_hx_t<OP1,OP2,OP3>
compose_f_gx_hx (const OP1& o1, const OP2& o2, const OP3& o3)
{
    return compose_f_gx_hx_t<OP1,OP2,OP3>(o1,o2,o3);
}

#include <iostream>
#include <list>
#include <algorithm>
#include <functional>
#include "compose21.hpp"
using namespace std;

int main()
{
    list<int> coll;
    list<int>::iterator pos;
    for(int i=20;i<=40;++i)
        coll.push_back(i);
    pos = find_if(coll.begin(),coll.end(),
        compose_f_gx_hx(logical_or<bool>(),
        bind2nd(equal_to<int>(),25),
        bind2nd(equal_to<int>(),35)));
    cout<<"num: "<<*pos<<endl;
    system("pause");
    return 0;
}

2,三种迭代器适配器:

1) Insert iterator 插入位置可以是容器的最前或最后,或是在某一特定位置上.

#include <iostream>
#include <vector>
#include <list>
#include <deque>
#include <set>
#include <algorithm>
using namespace std;

int main()
{
    list<int> coll1;
    // insert elements from 1 to 9 into the first collection
    for (int i=1; i<=9; ++i)
{
        coll1.push_back(i);
    }
    // copy the elements of coll1 into coll2 by appending them
    vector<int> coll2;
    copy (coll1.begin(), coll1.end(),      // source
          back_inserter(coll2));           // destination
    // copy the elements of coll1 into coll3 by inserting them at the front
    // - reverses the order of the elements
    deque<int> coll3;
    copy (coll1.begin(), coll1.end(),      // source
          front_inserter(coll3));          // destination
    // copy elements of coll1 into coll4
    // - only inserter that works for associative collections
    set<int> coll4;
    copy (coll1.begin(), coll1.end(),      // source
          inserter(coll4,coll4.begin()));  // destination
    return 0;
}

back_inserter的内部调用push_back(),在容器尾端插入元素,只有在提供有push_back()成员函数的容器中才能使用,这样的容器有:vector,deque,list. front_inserter的内部调用push_front(),在容器最前端插入元素,只有在提供有push_ front()成员函数的容器中才能使用,这样的容器有deque和list;一般性的inserter,作用是将元素插入”初始化时接受之第二参数”所指的位置的前方.它内部调用insert().

2)Stream iterator.这是用来读写流的迭代器.

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <iterator>
using namespace std;
int main()
{
vector<string> coll;
copy (istream_iterator<string>(cin),    // start of source
istream_iterator<string>(),       // end of source
back_inserter(coll));             // destination
sort (coll.begin(), coll.end());
unique_copy (coll.begin(), coll.end(),             // source
   ostream_iterator<string>(cout,"\n")); // destination
}

3)Reverse iterator

#include <iostream>
#include <vector>
#include <algorithm>
#include <iterator>
using namespace std;

int main()
{
    vector<int> coll;
    // insert elements from 1 to 9
for (int i=1; i<=9; ++i)
{
        coll.push_back(i);
    }
    // print all element in reverse order
    copy (coll.rbegin(), coll.rend(),        // source
          ostream_iterator<int>(cout," "));  // destination
    cout << endl;
}

3,移除元素

#include <iostream>
#include <list>
#include <algorithm>
#include <iterator>
using namespace std;
int main()
{
    list<int> coll;
    // insert elements from 6 to 1 and 1 to 6
for (int i=1; i<=6; ++i)
{
        coll.push_front(i);
        coll.push_back(i);
    }
    // print all elements of the collection
    copy (coll.begin(), coll.end(),ostream_iterator<int>(cout," "));
    cout << endl;
    list<int>::iterator end = remove (coll.begin(), coll.end(),3);//新的尾节点
    // print resulting elements of the collection
    copy (coll.begin(), end,ostream_iterator<int>(cout," "));
    cout << endl;
    // print number of resulting elements
    cout << "number of removed elements: "<< distance(end,coll.end()) << endl;
    // remove ``removed'' elements
    coll.erase (end, coll.end());
    // print all elements of the modified collection
    copy (coll.begin(), coll.end(),ostream_iterator<int>(cout," "));
    cout << endl;
}