Question

I have the following code:

vector<vector<Obj> > vectObjVects(10);
vectObjVects[0].reserve(100);

During runtime, at the third line of my code, I get a ‘Fatal Error’ thrown by the line _SCL_SECURE_VALIDATE_RANGE(_Pos < size());” in vector standard header which is presumably because it doesn’t like me trying to index into vectObjVects before a size has been set.

What is the recommended way to reserve space in the inner vectors of a 2D-vector before any values have been filled in?

EDIT – Obj class added as per request:

class Obj
{
public:
Obj(int a, int b):iA(a), iB(b) {} 
Obj():iA(0), iB(0) {}
int iA;
int iB;
};

Answer 1

There appear to be no errors in the code you have posted (see below).

The most likely explanations of your issue are:

• The code you’ve posted doesn’t exactly match what you are running.
• Some other code that you think is unrelated is interacting with your vectors, possibly by corrupting the memory they are stored in.

My suggestion is that you use the debugger to examine the state of vectObjVects just before the call to reserve. If that looks OK, step into the code for reserve and see what the values of _Pos and size() are. They should be 0 and 10 – if they’re not then that should point you in the right direction.

---

The following code compiles and runs exactly as expected:

#include <vector>

class Obj
{
public:
Obj(int a, int b):iA(a), iB(b) {} 
Obj():iA(0), iB(0) {}
int iA;
int iB;
};

int main() {
  std::vector<std::vector<Obj> > vectObjVects(10);
  vectObjVects[0].reserve(100);
}