Understanding Retained Memory in Functions

In the context of a function, `retains` refers to the fact that the function does not release or free the memory that it uses. Instead, it keeps hold of the memory and is responsible for deallocating it when it is no longer needed.

In other words, a function that retains memory does not return the memory to the heap or the stack after it has finished using it. This means that the function is responsible for managing the lifetime of the memory, which can be useful in certain situations but also requires careful management to avoid memory leaks.

For example, consider a function that allocates memory for a large data structure and then returns a pointer to that data structure to the caller. If the function does not release the memory when it is no longer needed, the memory will be retained by the function and the caller will be responsible for deallocating it later. This can lead to memory leaks if the caller forgets to deallocate the memory.

In contrast, a function that returns a pointer to memory that is allocated on the stack or the heap and then releases the memory when it is no longer needed (i.e., `malloc` and `free`) does not retain the memory. The memory is released back to the heap or the stack as soon as the function finishes using it, so the caller does not need to worry about managing the lifetime of the memory.