【函数】fill和fill_n填充之区别-白红宇

【函数】fill和fill_n填充之区别

阅读量：5012 次

发布时间：2019-06-12

本文共 1568 字，大约阅读时间需要 5 分钟。

fill对区间填充

原型:

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

填充区间[first,last)

示例：

#include 
     
      #include 
      
       #include 
       
        using namespace std;int main () {  vector
        
          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
         
          ::iterator it=myvector.begin(); it!=myvector.end(); ++it)    cout << " " << *it;  cout << endl;   return 0;}

fill_n可指定填充的个数

原型:

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

填充区间[first，first+n)

n为要填充的元素个数

示例：

#include 
     
      #include 
      
       #include 
       
        using namespace std;int main () {  vector
        
          myvector (8,10);        // myvector: 10 10 10 10 10 10 10 10  fill_n (myvector.begin(),4,20);     // myvector: 20 20 20 20 10 10 10 10  fill_n (myvector.begin()+3,3,33);   // myvector: 20 20 20 33 33 33 10 10  cout << "myvector contains:";  for (vector
         
          ::iterator it=myvector.begin(); it!=myvector.end(); ++it)    cout << " " << *it;  cout << endl;   return 0;}