向量下标超出范围错误,C

知道我做错了什么吗？

#include <vector>
#include <String>
#include <iostream>
#include <iomanip>
#include <fstream>
#include <sstream>
using namespace std;

//(int argc,char* argv[]
int main()
{
    fstream bookread("test.txt");
    vector<String> words;

    bookread.open("test.txt");
    if(bookread.is_open()){
        cout << "opening textfile";
        while(bookread.good()){
            String input;
            //getline(bookread,input);
            bookread>>input;
            //String cleanedWord=preprocess(input);         
            //char first=cleanedWord[0];
            //if(first<=*/
            //cout << "getTing words";
            //getWords(words,input);
        }
    }
    cout << "all done";

    words[0];

getchar();
}