标签：algorithm   stl   算法   

replace原型：

std::replace

template <class ForwardIterator, class T>
  void replace (ForwardIterator first, ForwardIterator last,
                const T& old_value, const T& new_value);

行为类似于：

template <class ForwardIterator, class T>
  void replace (ForwardIterator first, ForwardIterator last,
                const T& old_value, const T& new_value)
{
  while (first!=last) {
    if (*first == old_value) *first=new_value;
    ++first;
  }
}

replace_if原型：

std::replace_if

template <class ForwardIterator, class UnaryPredicate, class T>
  void replace_if (ForwardIterator first, ForwardIterator last,
                   UnaryPredicate pred, const T& new_value );

行为类似于：

template < class ForwardIterator, class UnaryPredicate, class T >
  void replace_if (ForwardIterator first, ForwardIterator last,
                   UnaryPredicate pred, const T& new_value)
{
  while (first!=last) {
    if (pred(*first)) *first=new_value;
    ++first;
  }
}

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
void replaceif()
{
    vector<int> vi{1,2,3,4,4,6};
    vector<int> v2{1,2,3,4,5,6};
    cout<<"vi=";
    for(int i:vi)
        cout<<i<<" ";
    cout<<endl;
    cout<<"v2=";
    for(int i:v2)
        cout<<i<<" ";
    cout<<endl;
    cout<<"vi.size()="<<vi.size()<<endl;
    cout<<"v2.size()="<<v2.size()<<endl;
    replace(vi.begin(),vi.end(),4,888);
    cout<<"after     replace(vi.begin(),vi.end(),4,888);"<<endl;
    cout<<"vi=";
    for(int i:vi)
        cout<<i<<" ";
    cout<<endl;
    replace_if(v2.begin(),v2.end(),[](int n){return n%2==0;},999);
    cout<<"after replace_if(v2.begin(),v2.end(),[](int n){return n%2==0;},999);"<<endl;
    cout<<"v2=";
    for(int i:v2)
        cout<<i<<" ";
    cout<<endl;
    cout<<"vi.size()="<<vi.size()<<endl;
    cout<<"v2.size()="<<v2.size()<<endl;

}

replace_copy原型：

std::replace_copy

template <class InputIterator, class OutputIterator, class T>
  OutputIterator replace_copy (InputIterator first, InputIterator last,
                               OutputIterator result,
                               const T& old_value, const T& new_value);

返回值为最后一个被覆盖元素的下一个位置的迭代器。

其行为类似于：

template <class InputIterator, class OutputIterator, class T>
  OutputIterator replace_copy (InputIterator first, InputIterator last,
                               OutputIterator result, const T& old_value, const T& new_value)
{
  while (first!=last) {
    *result = (*first==old_value)? new_value: *first;
    ++first; ++result;
  }
  return result;
}

replace_copy_if原型：

std::replace_copy_if

template <class InputIterator, class OutputIterator, class UnaryPredicate, class T>
  OutputIterator replace_copy_if (InputIterator first, InputIterator last,
                                  OutputIterator result, UnaryPredicate pred,
                                  const T& new_value);

返回值为最后一个被覆盖元素的下一个位置的迭代器。

template <class InputIterator, class OutputIterator, class UnaryPredicate, class T>
  OutputIterator replace_copy_if (InputIterator first, InputIterator last,
                                  OutputIterator result, UnaryPredicate pred,
                                  const T& new_value)
{
  while (first!=last) {
    *result = (pred(*first))? new_value: *first;
    ++first; ++result;
  }
  return result;
}

两者合成一个简单的例子：

#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
void replacecopyif()
{
    vector<int> vi{1,2,3,4,4,6};
    vector<int> vresult1(6);
    vector<int> vresult2(6);
    cout<<"vi=";
    for(int i:vi)
        cout<<i<<" ";
    cout<<endl;
    cout<<"vreult1=";
    for(int i:vresult1)
        cout<<i<<" ";
    cout<<endl;
    cout<<"vreult2=";
    for(int i:vresult2)
        cout<<i<<" ";
    cout<<endl;
    replace_copy(vi.begin(),vi.end(),vresult1.begin(),4,888);
    cout<<"after     replace(vi.begin(),vi.end(),vresult1.begin(),4,888);"<<endl;
    cout<<"vresult1=";
    for(int i:vresult1)
        cout<<i<<" ";
    cout<<endl;
    replace_copy_if(vi.begin(),vi.end(),vresult2.begin(),[](int n){return n%2==0;},999);
    cout<<"after replace_if(v2.begin(),v2.end(),vresult2.begin(),[](int n){return n%2==0;},999);"<<endl;
    cout<<"vresult2=";
    for(int i:vresult2)
        cout<<i<<" ";
    cout<<endl;
}

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//写的错误或者不好的地方请多多指导，可以在下面留言或者点击左上方邮件地址给我发邮件，指出我的错误以及不足，以便我修改，更好的分享给大家，谢谢。

转载请注明出处：http://blog.csdn.net/qq844352155

author:天下无双

Email:coderguang@gmail.com

2014-9-25

于GDUT

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STL algorithm算法replace,replace_if和replace_copy,replace_copy_if(49)

标签：algorithm   stl   算法   

原文地址：http://blog.csdn.net/qq844352155/article/details/39547057