STL: generate ,geterate_n

用来生成元素，并填充到一个序列中

generate：

1 template <class ForwardIterator, class Generator>
2   void generate ( ForwardIterator first, ForwardIterator last, Generator gen )
3 {
4   while (first != last) {
5     *first = gen();
6     ++first;
7   }
8 }

Generator gen生成器，是一个不接受参数，且有返回参数的函数，first和last是生成的范围。

generate_n:

 void generate_n (OutputIterator first, Size n, Generator gen);

first插入起始位置，n插入元素个数，gen元素生成器、

 1 #include<iostream>
 2 #include<vector>
 3 #include<algorithm>
 4 #include<time.h>
 5 #include <iterator>
 6 using namespace std;
 7
 8 int nextNum() {
 9     static int n = 1;
10     return n++;
11
12 }
13
14 class Range_generate{
15     private:
16         int m_Value;
17     public:
18         Range_generate(int value){m_Value=value;}
19         int operator()(){
22             return m_Value++;}
23 };
24
25 int main(){
26     for(int i=0;i<5;i++)
27         cout<<nextNum()<<" ";
28     srand((unsigned int) time(NULL));
29     vector<int> array(10,4);
30     cout<<endl;
31     int length=array.size();
32     cout<<length<<endl;
33     generate(array.begin(),array.end(),[]{return rand()%10;});
34     for(vector<int>::iterator ptr=array.begin();ptr!=array.end();){
35         cout<<*ptr<<" ";
36         ptr++;
37     }
38     cout<<endl;
39     generate(array.begin(),array.end(),Range_generate(1));
40     ostream_iterator<int> screen(cout," ");
41     copy(array.begin(),array.end(),screen);
42     system("pause");
43     return 0;
44 }