C++ looks up the example insert data method using std::forward_list

std: : forward_list is introduced

std::forward_list is a unidirectional linked list or forward list introduced in C++11. forward_list is fast to insert and delete table entries and consumes less memory space, but it can only traverse forward. Compared with other sequence containers (array, vector, deque), forward_list can insert, extract (extracting), move and delete members at any location in the container faster, so it is widely used in sorting algorithms. forward_list is a sequential container (sequence Container) that allows constant time to insert or delete elements at any point in the sequence (sequence Container). forward_list can be seen as a encapsulation of the C language style single linked list, providing only a limited interface and essentially no overhead compared to its implementation in C. When bidirectional iteration is not required, the container has higher space utilization than std::list.

The main disadvantage of forward_list is that it cannot randomly access any member in constant time. And storing link information consumes memory, especially when it contains a large number of small members. forward_list is deliberately not provided for the size() member function for efficiency reasons. The std::distance(_begin, _end) algorithm is needed to get the number of members contained by forward_list. Each element in forward_list holds information about locating the first and last element, and no direct random access is possible.

This article will introduce you about C++ using std::forward_list search insert data related content, share out for your reference to learn, the following words do not say, to 1 look at the detailed introduction.

Sample code:

//
// Forward_list.hpp
//  practice 
//
// Created by hanzhiqiang on 2017/6/11.
// Copyright © 2017 years  hanzhiqiang. All rights reserved.
//

#ifndef Forward_list_hpp
#define Forward_list_hpp

#include <stdio.h>
#include <iostream>
#include <forward_list>

using namespace std;

int main()
{
  forward_list<string> mList;
  mList.emplace_front("aaa");
  mList.emplace_front("bbb");
  mList.emplace_front("ccc");
  
  for (auto it = mList.begin(); it != mList.end(); it++)
  {
    cout<<*it<<endl;
  }
  
//  for (auto it = mList.before_begin(); it != mList.end(); it++)
//  {
//    cout<<*it<<endl;
//  }
  
//  auto itList = find(mList.begin(), mList.end(), "fff");
//  if (itList != mList.end()) \
//  {
//    mList.emplace_after(itList, "111");
//  }
//  else
//  {
//    mList.insert_after(mList.end(),"222");//c++ primer p 313  The result of inserting data into the end is unknown  error
//  }
  
  auto prev = mList.before_begin();
  auto curr = mList.begin();
  bool isInsert = false;
  while (curr != mList.end())
  {
    if (*curr == "fff")
    {
      curr = mList.insert_after(curr, "111");
      isInsert = true;
    }
    prev = curr;
    curr++;
  }
  
  if(!isInsert)
  {
    curr = mList.insert_after(prev, "222");// Insert data to the end successfully 
  }
  
  for (auto it = mList.begin(); it != mList.end(); it++)
  {
    cout<<" After inserting the element "<<*it<<endl;
  }
  
  cout<<"fuck"<<endl;
  return 0;
}

#endif /* Forward_list_hpp */

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