迭代矢量，删除某些项目，因为我去 [英] iterate vector, remove certain items as I go

问题描述

我有一个std :: vector m_vPaths;我会迭代这个向量，并调用:: DeleteFile（strPath）作为我去。如果我成功删除文件，我会从向量中删除它。我的问题是我可以绕过不得不使用两个向量？是否有不同的数据结构可能更适合我需要做什么？

I have a std::vector m_vPaths; I will iterate this vector and call ::DeleteFile(strPath) as I go. If I successfully delete the file, I will remove it from the vector. My question is can I get around having to use two vectors? Is there different data structure that might be better suited for what I need to do?

示例：
使用迭代器几乎做我想要的，但问题是一次您使用迭代器擦除，所有迭代器变得无效。

example: using iterators almost does what I want, but problem is once you erase using an iterator, all iterators become invalid.

 std::vector<std::string> iter = m_vPaths.begin();
    for( ; iter != m_vPaths.end(); iter++) {
        std::string strPath = *iter;
        if(::DeleteFile(strPath.c_str())) {
            m_vPaths.erase(iter);   
                //Now my interators are invalid because I used erase,
                //but I want to continue deleteing the files remaining in my vector.    
        }
    }

我可以使用两个向量，一个问题，但是有更好的，更有效的方法来做我想做的吗？

I can use two vectors and I will no longer have a problem, but is there a better, more efficient method of doing what I'm trying to do?

btw，但是不清楚，m_vPaths声明这样在我的类）：

btw, incase it is unclear, m_vPaths is declared like this (in my class):

std::vector<std::string> m_vPaths;

推荐答案

查看 std :: remove_if ：

#include <algorithm> // for remove_if
#include <functional> // for unary_function

struct delete_file : public std::unary_function<const std::string&, bool> 
{
    bool operator()(const std::string& strPath) const
    {
        return ::DeleteFile(strPath.c_str());
    }
}

m_vPaths.erase(std::remove_if(m_vPaths.begin(), m_vPaths.end(), delete_file()),
                m_vPaths.end());

使用 std :: list 来停止无效迭代器问题，虽然你失去了随机访问。 （和一般的缓存性能）

Use a std::list to stop the invalid iterators problem, though you lose random access. (And cache performance, in general)

对于记录，你实现代码的方式是： p>

For the record, the way you would implement your code would be:

typedef std::vector<std::string> string_vector;
typedef std::vector<std::string>::iterator string_vector_iterator;

string_vector_iterator iter = m_vPaths.begin();
while (iter != m_vPaths.end())
{
    if(::DeleteFile(iter->c_str()))
    {
        // erase returns the new iterator
        iter = m_vPaths.erase(iter);
    }
    else
    {
        ++iter;
    }
}

$ b < //en.cppreference.com/w/cpp/algorithm/remove> std :: remove_if （重新发明轮子不好）。

But you should use std::remove_if (reinventing the wheel is bad).

这篇关于迭代矢量，删除某些项目，因为我去的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！