How can I enable and disable bounds checking for `std::vector` in C ?

Compiler Options for Bound Checking Array Access in C Vector

The C standard library provides the std::vector type, a dynamic array that ensures memory safety. However, accessing elements with operator[] carries an inherent risk of undefined behavior if the index is out of bounds.

Enable Bounds Checking in Debug Mode

To enable bounds checking for operator[] in Visual Studio, the macro _SECURE_SCL can be defined to a non-zero value. This will enforce range checking during runtime, resulting in a std::out_of_range exception when an invalid index is accessed.

Disable Bounds Checking in Release Mode

To optimize performance in release builds, bounds checking can be disabled by setting _SECURE_SCL to 0. This eliminates the runtime overhead associated with range verification.

Example:

<code class="cpp">// Enable bounds checking in debug mode (assuming Visual Studio 2008 or earlier)
#ifdef _DEBUG
#define _SECURE_SCL 1
#endif

// ...
std::vector<:vector>> v;
v[0][1]; // Throws `std::out_of_range` if i or j is out of bounds</:vector></code>

Note:

• Visual Studio 2005 and 2008 enable bounds checking by default in both debug and release builds.
• In Visual Studio 2010 onward, bounds checking is enabled by default in debug builds but disabled in release builds. The macro _ITERATOR_DEBUG_LEVEL controls this behavior.

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