练习3.1

//Essential c++ 3.1#include<iostream>#include<fstream>#include<map>#include<string>#include<set>using namespace std;int main(){       const int elemsize=6;    string notneed[elemsize]={"a","an","or","the","and","but"};    set<string> filter(notneed,notneed+elemsize);    string word;    map<string,int> word_anly;        //step 1    ifstream inputfile("./input.txt");    if(!inputfile)  cerr<<"input wrong"<<endl;       while(inputfile >> word)    {        if(filter.count(word))        {            continue;        }        else        {            word_anly[word]++;        }    }        //step2    ofstream outputfile("./output.txt");    if(!outputfile)  cerr<<"output wrong"<<endl;        for(map<string,int>::iterator it=word_anly.begin();        it!=word_anly.end();it++)    {        outputfile<<it->first<<"    "<<it->second<<endl;    }    return 0;}