How does C++ memory management interact with the operating system and virtual memory?

C++ memory management interacts with the operating system, manages physical memory and virtual memory through the operating system, and efficiently allocates and releases memory for the program. The operating system divides physical memory into pages and pulls in the pages requested by the application from virtual memory as needed. C++ uses the new and delete operators to allocate and free memory, requesting memory pages from the operating system and returning them respectively. When the operating system frees physical memory, it swaps less used memory pages into virtual memory.

How C++ memory management interacts with the operating system and virtual memory

In C++, memory management involves allocating and freeing programs for use of memory. It interacts closely with the operating system and virtual memory to provide efficient and predictable program execution.

Memory management in the operating system

The operating system is responsible for managing the physical memory of the computer. It divides memory into pages, typically 4KB in size. Applications request memory from the operating system in units of pages. When an application requests a memory page that is not in physical memory, the operating system brings it in from virtual memory on disk.

Virtual Memory

Virtual memory is a space allocated on the hard disk to store memory pages that are not currently in physical memory. When the operating system needs to free up physical memory, it swaps less used memory pages into virtual memory. This makes physical memory available for other high-priority programs that need it.

Memory management of C++

C++ provides a library function new and delete for allocating and releasing memory . The new operator requests a memory page from the operating system, and the delete operator frees the memory and returns it to the operating system.

Interaction with the operating system and virtual memory

When a program allocates memory using the new operator, the operating system checks whether There are pages available. If no page is available, the operating system loads a page from virtual memory. When a program releases memory using the delete operator, the operating system marks the memory page as available and swaps it into virtual memory as needed.

Practical Case: Virtual Memory Usage Example

The following code example demonstrates how to use C++ and virtual memory:

#include <iostream>

int main()
{
  // 分配 100 MB 内存
  char *array = new char[1024 * 1024 * 100];

  // 使用分配的内存

  // 释放内存
  delete[] array;

  return 0;
}

In this example, the code Allocate 100 MB of memory using the new operator. Since allocating such a large amount of memory at once is likely to result in insufficient physical memory, the operating system must page in several pages from virtual memory. The code then uses the allocated memory and finally frees it using the delete operator.

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