Implementing Bounds Checking in std::vector Operator[] for Debug Mode

In C , the std::vector class offers automatic bounds checking through its at() method. However, the operator[] method allows for unchecked array access, potentially leading to undefined behavior. Developers often seek a way to enable bounds checking for operator[] in debug mode without compromising performance in release mode.

To address this issue, Visual Studio 2005 and 2008 implement bounds checking for operator[] natively in both debug and release builds. This is governed by the macro _SECURE_SCL, which can be set to 0 to disable bounds checking and revert to the unchecked behavior.

In subsequent versions, such as Visual Studio 2010, Microsoft plans to disable bounds checking by default in release builds while retaining it in debug mode. A new macro, _ITERATOR_DEBUG_LEVEL, will replace _SECURE_SCL to control this functionality.

By adopting this approach, developers can ensure that out-of-range access to std::vector elements triggers a std::out_of_range exception in debug mode, providing valuable error detection while maintaining efficient performance in release builds.