Question

I have a vector< vector<string> > and want to add a string to the inside vector with push_back(). This is what I tried:

vector< vector<string> > sorted_word_vecs;
char word_read[MAX_WORD_LENGTH];


for(int i = 0; i < num_of_pipes; i++)
{
    while (fgets(word_read, MAX_WORD_LENGTH, pipe_read_from_sort[i]) != NULL)
    {
        word = word_read;
        sorted_word_vecs[i].push_back(word);
    }
}

But I always get a seg fault (I’ve narrowed it down to the push_back line with cout’s). Is this the wrong way to do it?

Answer 1

You need to create space in the outer vector:

vector< vector<string> > sorted_word_vecs;
char word_read[MAX_WORD_LENGTH];
sorted_word_vecs.resize(num_of_pipes);

Not doing this means that you are asking for an element that doesn’t exist with the sorted_words_vecs[i].