sort function C++ segmentation fault

Question

In this code, for vector size, n >=32767, it gives segmentation fault, but upto 32766, it runs fine. What could be the error? This is full code.

#include

        

Answer 1

C++ acts weird sometimes. I got Segmentation fault in basic_string.h file! I was upgrading my code base to GCC 5.4.0 from GCC 4.2.1 and suddenly this SEG FAULT occurred and I was wondering why the same code was working earlier and now it is breaking inside C++ own STL. Then I looked up the back trace and found that it was coming from std::sort for vector of pointers, which was using custom comparator to compare the pointers on the basis of fetching the object's name by member function ptr->GetName(). This GetName() was returning a string.

I spent a whole day on figuring out what maybe the change in basic_string file to cause this fault. Then I got to know about this "Strict Weak Ordering" thing and I changed my comparator function accordingly. Still no luck.

Then I tweaked around and changed the original comparator function to a Functor. And now, it worked. I don't know exactly the reason behind it but it worked.

Here is my original comparator function :

bool swap (CLwPatternObj *a, CLwPatternObj *b){
    return a->GetName() < b->GetName() ) 
}

And here is the new Function Object.

class CLwPatternComparator
{
public:
    bool operator() (CLwPatternObj *a, CLwPatternObj *b) 
    {
        return a->GetName() < b->GetName();
    }
};

Same logic, but it works with Function Object.