Question

I’m using a vector in my program like this:

vector<vector<string> > values;
values[0].push_back("test words");

when i run the code, it shows “segment fault”

then i try to gdb it and i got this:

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_INVALID_ADDRESS at address: 0x0000000000000008
0x00000001000035be in std::vector<std::string, std::allocator<std::string> >::push_back (this=0x0, __x=@0x7fff5fbff330) at stl_vector.h:602
602     if (this->_M_impl._M_finish != this->_M_impl._M_end_of_storage)

What is going on here ?

Answer 1

There are no elements in values, which means this results in out of bounds access:

values[0].push_back("test words");

You need to push_back() an empty vector<string> into values:

values.push_back(vector<string>());
values[0].push_back("test words");

or create values with at least one entry (see vector constructors):

vector<vector<string> > values(1);