C++ Question, Binary Searching!?

here is my code, i am trying to binary search a vector to see if it is finding the right stuff.

i am using std::sort in main, so it is sorted

here is my code: it is currently throwing a segfault or not running at all.. but it compiles fine

//boolean to test incoming words if they are, indeed a stop_word

bool isStopWord(string word, vector<string> &STOP_WORDS){

//sort( STOP_WORDS.begin(), STOP_WORDS.end() );

//boolean for return

bool retbool = false;

//binary search this badboy

int low = 0;

int high = STOP_WORDS.size();

while(low<=high){

int middle = low + ((high-low)/2);

if(word < STOP_WORDS[middle]){

high = middle-1;

}

else if(STOP_WORDS[middle] < word){

low=middle+1;

}

else{

retbool = true;

}

}

return retbool;

}