How Does `delete[]` Know the Size of a Heap-Allocated Array in C ?

How Heap Allocation Manages Array Size?

In C , when creating arrays using new, the system allocates memory on the heap. Arrays allocated on the heap require explicit deallocation using delete[]. However, how does delete[] automatically determine the size of the array being deleted without explicitly specifying it?

Storing Memory Allocation Information

The answer lies in the way memory is managed on the heap. When allocating memory for an array using new, the allocator maintains information about the allocated memory size. This information is typically stored in a header or metadata segment just before the actual array data. The allocator knows how much memory was requested and keeps track of it for later use.

Deallocation Process

When delete[] is called to deallocate an array allocated on the heap, it uses the stored metadata to determine the size of the array. By referencing this information, delete[] can free the correct amount of memory, ensuring that no memory leaks occur.

Standardization

The process of storing and referencing memory allocation information for heaps is not standardized in the C language. However, most modern C implementations use a similar approach, ensuring that delete[] functions as expected across different platforms and compilers. This allows developers to rely on this behavior without worrying about the specific implementation details.

The above is the detailed content of How Does `delete[]` Know the Size of a Heap-Allocated Array in C ?. For more information, please follow other related articles on the PHP Chinese website!