How can I exclude words with apostrophes when reading into a table of strings?

ifstream fin;
    string temp;
    fin.open("engldict.txt");
    if(fin.is_open())
    {
        bool apos = false;
        while(!fin.eof())
        {
            getline(fin, temp, '\n');
            if(temp.length() > 2 && temp.length() < 7)
            {
                for(unsigned int i = 0; i < temp.length(); i++)
                {
                    if(temp.c_str()[i] == '\'')
                        apos = true;
                }

                if(!apos)
                    dictionary.insert(temp);
            }
        }
    }

This code gives me a runtime error: Unhandled exception at 0x00A50606 in Word Jumble.exe: 0xC0000005: Access violation reading location 0x00000014.

and throws me a break point at:

size_type size() const _NOEXCEPT
        {   // return length of sequence
        return (this->_Mysize);
        }

within the xstring header.

This exception is thrown no matter what character I use, so long as it is present within the words I am reading in.

I am aware that it is probably a super simple fix, but I just really need another set of eyes to see it. Thanks in advance.