I’m trying to wrap my head around the C++ standard’s description of allocation functions. The part about regular allocation functions makes sense to me. But I’m completely lost when it comes to extended allocation functions.
The standard talks about how new-expressions work with normal allocation functions. It explains how much space they request and some rules about alignment. That’s all clear enough.
But then it mentions these extended allocation functions. It says something about the size argument being no greater than the sum of sizes for omitted calls plus the extended call size and some padding.
This whole concept of extended allocation is throwing me for a loop. What exactly are these extended allocation functions? How do they differ from regular ones? And why would we need them?
If anyone could break this down in simpler terms, I’d really appreciate it. Maybe an example of when you’d use an extended allocation function vs a regular one would help too.
// Regular allocation example (I think?)
int* regularAlloc = new int[5];
// Extended allocation example???
// I have no idea what this would look like
Extended allocation functions are indeed a more advanced concept in C++ memory management. They’re designed to provide greater flexibility when allocating memory, particularly for scenarios requiring specific alignment or additional space for internal bookkeeping. In my experience, these functions are rarely used in everyday programming. They’re more commonly encountered when developing custom allocators or working on performance-critical systems where memory layout is crucial. A typical use case might be in embedded systems or game development, where you need precise control over memory allocation to optimize performance. For instance, when I was working on a real-time rendering engine, we used extended allocation to ensure proper alignment for GPU-related data structures. While it’s good to be aware of their existence, don’t worry if you’re not using them regularly. Most C++ developers can go their entire careers without directly interacting with extended allocation functions.
I’ve grappled with extended allocation functions myself, and they can be quite tricky to understand at first. From my experience, the key difference is that extended allocation functions allow for more flexibility in memory management.
Regular allocation functions are straightforward - you request a chunk of memory, and that’s what you get. Extended allocation functions, on the other hand, can handle more complex scenarios where you might need additional memory for bookkeeping or alignment purposes.
In practice, I’ve found extended allocation functions useful when implementing custom memory managers or when dealing with complex data structures that require special alignment or padding. For instance, when working on a game engine, we used extended allocation to ensure proper alignment for SIMD operations.
Here’s a simplified example of what an extended allocation might look like:
This allows you to specify both size and alignment requirements. The standard ensures that the allocator can handle these more complex requests efficiently.
While you might not use extended allocation functions directly in everyday coding, understanding them can be crucial when diving into low-level memory management or optimizing performance-critical systems.
Hey Mike, extended allocation funcs are like super-charged versions of regular ones. they give u more control over memory stuff, like alignment n extra space for bookkeeping. u might use em when u need special memory layouts or custom allocators. don’t sweat it if u don’t use em often tho - they’re more for advanced memory tricks!