Application of C++ function memory allocation and destruction in containers and algorithms

In C, memory is allocated and destroyed through dynamic allocators (new and delete), which are used to manage memory in containers and algorithms. Containers (such as vectors, lists, and maps) handle memory automatically, using the RAII principle for allocation and deallocation. Algorithms can use dynamic allocation (such as merge sort) and function pointers (such as transform) to process data. By understanding these applications, programmers can manage memory in C more efficiently.

Application of C function memory allocation and destruction in containers and algorithms

Memory management

In C, memory is allocated and destroyed through a dynamic allocator, which allows the programmer to control memory at runtime. Two of the most commonly used allocators are new and delete.

• new is used to allocate memory and returns a pointer to the allocated memory.
• delete is used to release memory previously allocated by new.

Containers

Containers are structures used to store data, such as vector, list and map. They handle memory allocation and destruction automatically, using the RAII (Resource Acquisition Is Initialization) principle. This means that when the container object is created, it automatically allocates the required memory. When an object is destroyed, it automatically frees the memory.

The following is an example using the vector container:

#include <vector>

int main() {
  std::vector<int> numbers;  // 创建一个 vector 容器来存储整数
  
  for (int i = 0; i < 10; i++) {
    numbers.push_back(i);  // 将元素添加到 vector
  }
  
  // 容器自动释放分配的内存
  return 0;
}

Algorithm

The algorithm is used Functions for processing data, such as sort, find, and transform. They can use both dynamic allocation and function pointers.

Dynamic Allocation

Some algorithms require internal allocation of memory, such as merge sort.

The following is an example of using the merge sort algorithm:

#include <algorithm>
#include <vector>

int main() {
  std::vector<int> numbers = {1, 5, 2, 4, 3};
  
  std::sort(numbers.begin(), numbers.end());  // 对 vector 进行排序，内部使用动态分配
  
  for (int number : numbers) {
    std::cout << number << " ";  // 输出排序后的数组
  }
  
  std::cout << std::endl;
  return 0;
}

Function pointer

The algorithm can also use function pointers to Specify how to process the data, such as transform.

The following is an example of using the transform algorithm:

#include <algorithm>
#include <vector>

int square(int n) { return n * n; }

int main() {
  std::vector<int> numbers = {1, 2, 3, 4, 5};
  
  std::transform(numbers.begin(), numbers.end(), numbers.begin(), square);  // 对 vector 中的每个元素执行 square 函数
  
  for (int number : numbers) {
    std::cout << number << " ";  // 输出转换后的数组
  }
  
  std::cout << std::endl;
  return 0;
}

By understanding the application of function memory allocation and destruction in containers and algorithms, programs This allows programmers to manage memory in C more efficiently.

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