C++ memory management: when to use new and delete

New and delete are used in C to manage memory. new is used to dynamically allocate objects in heap memory, and delete is used to release the memory block allocated using new to avoid memory leaks. The new operator requests memory from the operating system and returns a pointer; the delete operator returns a pointer to a memory block and releases the memory. To ensure correct memory management, always use delete to free memory allocated using new to avoid undefined behavior caused by freeing unallocated memory.

C Memory Management: When to Use New and Delete

In C, managing memory is essential for writing robust and efficient programs Crucial. The new and delete operators are the primary tools for managing memory in C, and understanding their correct usage is critical to avoiding memory leaks and program crashes.

When to use new

new operator is used to dynamically allocate objects in heap memory. Heap memory is a memory area managed by the operating system when a program is running. When using new, the compiler is responsible for requesting the required memory from the operating system and returning a pointer to the newly allocated memory block.

Here's how to allocate an int array using the new operator:

int* arr = new int[10];

When to use delete The

delete operator is used to free a block of memory previously allocated using new. It returns the memory block pointed to by the pointer to the operating system to prevent memory leaks in the program.

Must always use delete to free all memory allocated using new. Otherwise, the program may crash due to memory leaks.

The following is how to use the delete operator to release the memory allocated by the array arr:

delete[] arr;

Practical case

Suppose we have a function that takes an integer n and creates an array containing n elements.

int* createArray(int n) {
  int* arr = new int[n];  // 使用 new 分配内存
  return arr;
}

Outside the function, we use this function to create the array and free the memory after use:

int* arr = createArray(10);

// 使用数组

delete[] arr;  // 释放内存

In the above example, we use new and delete Correctly manage the memory of the array to prevent memory leaks.

Points to note

• Always use delete to release memory allocated using new.
• Make sure not to attempt to free unallocated memory, otherwise undefined behavior will result.
• In C 11, new and delete can be optimized via smart pointers such as unique_ptr and shared_ptr .

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