Question

I am trying to use a standard exception class in c++ like:

#include <iostream>
#include <exception>
using namespace std;
int main(){
    int a[6]={12,3,2,4,5,6};
    int n=6;
    try{
     cout<<a[6]<<"  ";

    }
    catch(std::exception & exc)
     {
         cout<<exc.what();

     }

     return 0;  
    }

But instead of showing me the error – “out of index” ,it throws a run time error, saying that the “variable a is uninitialized” ,why? I have declared it as an array and make initialization of it. Please give me some advise why it does so?

Answer 1

Accessing a[6] is undefined behaviour, since the only valid indices for a are 0..5.

You shouldn’t expect a[6] to perform any bounds checking, much less throw a C++ exception on out-of-bounds array access.

If do you want automatic bounds checking, make a into std::vector<int> and use a.at(index) to access its elements.