为什么我的ifstream程序以错误的顺序读取单词？

Question

I employed a map to keep count of how many times each unique word appears in the .txt file... Its working and its reading in from the file, but the output is in the wrong order.

#include <map>
#include <cstdlib>
#include <iostream>
#include <fstream>
#include <vector>
#include <string>
using namespace std;

typedef map<string, int> StrIntMap;

void CountWords(ifstream& myStream, StrIntMap& wordMap)
{
int wCount = 0;
string word;

while (!myStream.eof())
{
    if(myStream >> word)
    {
        wCount++;
        ++wordMap[word];
    }
    else
    {
        cout << "Not Open" << endl;
    }
}

for (StrIntMap::iterator i = wordMap.begin(); i != wordMap.end(); ++i)
{
    cout << i->first << " || " << i->second << endl;
}

cout << "Number of Words: " << wCount << endl;
}

The main file opens the ifstream and calls CountWords.

Answer 1

The file is being read in order. The map does not store elements by the order inserted, but by a binary tree that sorts them for log(n) retrieval.

To read unique words back in order, the easiest way would to be to either add a separate vector where you only insert unique words not yet in the map, or store the position as part of the struct when you insert into the map, then output them by order of position.

To read all words (unique or non unique) back in order, forget the map and just insert and call from a vector.