函数备份：按照指定的分隔符，将字符串进行切分

vector<string>Preprocess:: mySplit(string s,set<string> stopwords)
{
    vector<string> wordCollection;
    trim(s," ");

    int nPosBegin=0;
    int nPosEnd=s.find(',',nPosBegin);
    while(nPosEnd!=string::npos)
    {
        string temp=s.substr(nPosBegin,nPosEnd-nPosBegin);
        trim(temp," ");
        if(temp!="")
        {
            wordCollection.push_back(temp);
        }


        nPosBegin=s.find_first_not_of(',',nPosEnd);
        if(nPosBegin==string::npos)
        {
            nPosEnd=string::npos;
        }
        else
        {
            nPosEnd=s.find(',',nPosBegin);

        }

    }
    if(nPosBegin!=string::npos&&nPosEnd==string::npos)//结尾缺少分割号，添加该词
    {
        string temp=s.substr(nPosBegin,s.size()-nPosBegin);
        trim(temp," ");
        if(temp!="")
        {
            wordCollection.push_back(temp);
        }


    }

    return wordCollection;

}