STL_算法_填充新值(fill、fill_n、generate、generate_n)

C++ Primer 学习中。。。

 

简单记录下我的学习过程 (代码为主)

所有容器适用

fill(b,e,v)             //[b,e)   填充成v
fill_n(b,n,v)           //[b,b+n) 填充成v
generate(b,e,p)         //[b,e)   按照p方法填充
generate_n(b,n,p)       //[b,b+n) 按照p方法填充

/**------http://blog.csdn.net/u010579068------**/
#include<iostream>
#include<cstdio>
#include<string>
#include<vector>
#include<list>
#include<deque>
#include<ctime>
#include<algorithm>
using namespace std;

/*****************************************
//所有容器适用
fill(b,e,v)             //[b,e) 填充成v
fill_n(b,n,v)           //[b,b+n) 填充成v
generate(b,e,p)         //[b,e) 按照p方法填充
generate_n(b,n,p)       //[b,b+n) 按照p方法填充

*****************************************/
/**----------------------------------------------------------------------------------

----------------------------------------------------------------------------------**/
/*************************************************************************************
std::fill                     所有排序容器适用                           algorithm
--------------------------------------------------------------------------------------
template < class ForwardIterator, class T >
  void fill ( ForwardIterator first, ForwardIterator last, const T& value );

//eg：
template < class ForwardIterator, class T >
  void fill ( ForwardIterator first, ForwardIterator last, const T& value )
{
  while (first != last)  *first++ = value;
}
*************************************************************************************/

/*************************************************************************************
std::fill_n                     所有排序容器适用                           algorithm
--------------------------------------------------------------------------------------
template < class OutputIterator, class Size, class T >
  void fill_n ( OutputIterator first, Size n, const T& value );

//eg：
template < class OutputIterator, class Size, class T >
  void fill_n ( OutputIterator first, Size n, const T& value )
{
  for (; n>0; --n)  *first++ = value;
}
*************************************************************************************/

/*************************************************************************************
std::generate                     所有排序容器适用                          algorithm
--------------------------------------------------------------------------------------
template <class ForwardIterator, class Generator>
  void generate ( ForwardIterator first, ForwardIterator last, Generator gen );

//eg：
template <class ForwardIterator, class Generator>
  void generate ( ForwardIterator first, ForwardIterator last, Generator gen )
{
  while (first != last)  *first++ = gen();
}
*************************************************************************************/

/*************************************************************************************
std::generate_n                    所有排序容器适用                          algorithm
--------------------------------------------------------------------------------------
template <class OutputIterator, class Size, class Generator>
  void generate_n ( OutputIterator first, Size n, Generator gen );

//eg：
template <class OutputIterator, class Size, class Generator>
  void generate_n ( OutputIterator first, Size n, Generator gen )
{
  for (; n>0; --n)  *first++ = gen();
}
*************************************************************************************/

// function generator:
int RandomNumber ()
{
    return (rand()%100);
}

// class generator:
struct c_unique
{
    int current;
    c_unique()
    {
        current=0;
    }
    int operator()()
    {
        return ++current;
    }
} UniqueNumber;

int current(0);
int Unique_Number ()
{
    return ++current;
}

int main()
{
    vector<int> myvector (8);                       // myvector: 0 0 0 0 0 0 0 0

    fill (myvector.begin(),myvector.begin()+4,5);   // myvector: 5 5 5 5 0 0 0 0
    fill (myvector.begin()+3,myvector.end()-2,8);   // myvector: 5 5 5 8 8 8 0 0

    cout << "myvector contains:";
    for (vector<int>::iterator it=myvector.begin(); it!=myvector.end(); ++it)
        cout << " " << *it;

    cout << endl;
    /**---------------------------------------------------------------------------------**/
    deque<int> mydeque (8,10);        // mydeque: 10 10 10 10 10 10 10 10

    fill_n (mydeque.begin(),4,20);     // mydeque: 20 20 20 20 10 10 10 10
    fill_n (mydeque.begin()+3,3,33);   // mydeque: 20 20 20 33 33 33 10 10

    cout << "mydeque contains:";
    for (deque<int>::iterator it=mydeque.begin(); it!=mydeque.end(); ++it)
        cout << " " << *it;

    cout << endl;
    /**---------------------------------------------------------------------------------**/

    srand ( unsigned ( time(NULL) ) );

//   vector<int> myvector (8);
    vector<int>::iterator it;

    generate (myvector.begin(), myvector.end(), RandomNumber);

    cout << "myvector contains:";
    for (it=myvector.begin(); it!=myvector.end(); ++it)
        cout << " " << *it;

    generate (myvector.begin(), myvector.end(), UniqueNumber);

    cout << "\nmyvector contains:";
    for (it=myvector.begin(); it!=myvector.end(); ++it)
        cout << " " << *it;

    cout << endl;
    /**---------------------------------------------------------------------------------**/

    int myarray[9];

    generate_n (myarray, 9, Unique_Number);

    cout << "myarray contains:";
    for (int i=0; i<9; ++i)
        cout << " " << myarray[i];

    cout << endl;

    return 0;
}
/******
Output:
    myvector contains: 5 5 5 8 8 8 0 0
    mydeque contains: 20 20 20 33 33 33 10 10
    myvector contains: 64 12 31 25 35 67 20 6
    myvector contains: 1 2 3 4 5 6 7 8
    myarray contains: 1 2 3 4 5 6 7 8 9


******/