Segmentation fault in reading from a file into a string array - c++

Question

I am having a bizarre error in assigning values in an array of strings. It assigns two or three intermittently and then crashes.
I am trying to implement a simple unsorted dictionary like structure using two parallel arrays(one of strings and one of integers)
Here is where in the code I think the fault is occurring.
std::ifstream infile1("out1.tmp");
std::string word;
while (getline(infile1,word)){
std::istringstream iss(word);
printf("stream created\n");
if (!(iss >> bookone.keys[i]))
break;
i++;
}
bookone is a dictionary object that has the public fields:keys and index. Even if I move the variable assignment into the class it errors in the same way.
The part that confuses me the most is that it appears to work the first few iterations.
strace provides this:
open("out1.tmp", O_RDONLY) = 5
read(5, "This\nEtext\nfile\nis\npresented\nby\n"..., 8191) = 8191
write(1, "stream created\n", 15stream created
) = 15
write(1, "stream created\n", 15stream created
) = 15
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0xd36ff8} ---
+++ killed by SIGSEGV +++
[1] 16430 segmentation fault strace ./book macbeth.txt othello.txt
and valgrind gives me a bunch of these:
==16499== Invalid read of size 8
==16499== at 0x4EAB634: std::basic_istream<char, std::char_traits<char> >& std::operator>><char, std::char_traits<char>, std::allocator<char> >(std::basic_istream<char, std::char_traits<char> >&, std::basic_string<char, std::char_traits<char>, std::allocator<char> >&) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.20)
==16499== by 0x401673: main (in /home/luna/sauce/books/book)
==16499== Address 0x5a00ca8 is 24 bytes before a block of size 568 alloc'd
==16499== at 0x4C28C20: malloc (vg_replace_malloc.c:296)
==16499== by 0x56C106C: __fopen_internal (iofopen.c:73)
==16499== by 0x401555: main (in /home/luna/sauce/books/book)