C++ exception caught

ROOT
1

Hi,

I have a macro that used to run fine in root before and now suddenly it is throwing an error as
’Error: C++ exception caught’ and it terminates.

What does this mean? And how can I avoid it?

  • Sujeewa
2

Hi again,

Ok, so I saw this post by Philippe (osdir.com/ml/lang.c++.root/2006-02/msg00007.html) and added the line gROOT->ProcessLine(".exception");
to my macro.

Now it fails with an error-
Progress: 20%
terminate called after throwing an instance of 'std::out_of_range’
what(): vector::_M_range_check

What is going on here? Any insight will be much appreciated!

  • Sujeewa
3

Hi,

[quote]terminate called after throwing an instance of 'std::out_of_range’
what(): vector::_M_range_check[/quote]This means that your code (directly or indirectly) is trying to access an element of an std::vector object that is beyond the number of actual elements in the vector.

Cheers,
Philippe.

4

It’s because you are trying to access an element in a vector that does not exist. For exemple, you defined vector a with 5 entries and you are trying to read a.at(5). But the index for a vector start from 0, so 5 (in this example) is not valid. Then you get this seg fault. The 5th object is a.at(4), as the first is a.at(0)

Cheers.

S Poss.

5

Thanks guys!

So in general, is it a good thing to add the line gROOT->ProcessLine(".exception"); ? This will give me more information on why my code actually fails, right?

  • Sujeewa
6

Hi,

Yes, it does give more information but on the other hand does not allow to continue using the same session (i.e. it forces you to restart ROOT).

Cheers,
Philippe.

7

I see. Thanks, Philippe!