CODEWITHSUNDEEP
c++arraysexception
user1558168
user1558168

Reputation: 67

c++ out of range exception

I'm creating a function which iterates through a grid of points and returns the indices of all adjacent points. For the edge of the grid, there are adjacent points which do not exist, so I have created a few try blocks to handle these cases. Here is the code:

try {
            all_below[j] = Mesh.matrix[r[i]][c[i] - j];
        }
        catch (const std::out_of_range& oor) {
            below = NAN;
            below_k = NAN;
        }

But whenever I try to run the program, the catch statement doesn't catch the exception and the program crashes (because Mesh.matrix is out of range). What am I doing wrong?

Edit:

matrix is a 2D vector of int.

Upvotes: 1

Views: 2999

Answers (3)

ohmcodes
ohmcodes

Reputation: 79

vector<int> vec;
vec.push_back(1);
vec.push_back(2);

try
{
    cout << vec.at(2) << endl;
}
catch (const out_of_range& e)
{
    cerr << e.what() << endl;
}

Upvotes: -1

Vlad from Moscow
Vlad from Moscow

Reputation: 311126

If all_below and Mesh.matrix are arrays then arrays do not throw any exception if you are using an index outside the available range.

And as noted @Mooing Duck the subscript operator of vectors also does not throw an exception. It is member function at() that throws an exception.

Upvotes: 3

PaulMcKenzie
PaulMcKenzie

Reputation: 35455

std::vector does not throw exceptions on out-of-bounds access using vector's operator [ ]. If you want an exception to be thrown, then use the vector::at() function instead of [ ].

Upvotes: 0

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