Out of Bounds Access in C-Style Arrays

When you attempt to access an element outside the bounds of a C-style array, you are invoking undefined behavior. This means that the language makes no guarantees about what will happen.

In practice, several things could occur:

1. Your program might crash immediately with a segmentation fault.
2. Your program might seem to work correctly, but you're actually accessing and modifying memory that doesn't belong to your array. This can lead to strange bugs that are hard to diagnose.
3. Your program might behave differently every time you run it.

Here's an example:

1int main() {
2  int arr[3] = {1, 2, 3};
3  
4  //  Out of bounds access
5  std::cout << arr[5];
6}

In this case, arr[5] is accessing memory beyond the end of the array, which is undefined behavior.

To avoid this, always ensure your array accesses are within the valid bounds of the array. If you need runtime bounds checking, consider using std::vector or std::array instead, which offer .at() for bounds-checked access.