What should you pay attention to when a C++ function returns a pointer?

In C, when a function returns a pointer, you need to pay attention to the following: the pointer must point to a valid object, otherwise undefined behavior will result. After a function returns a pointer, do not modify the object pointed to by the pointer, otherwise other code will be affected. The caller is responsible for managing the memory and releasing it when it is no longer needed. Using shared_ptr smart pointers to manage memory can avoid memory leaks.

Things to note when C functions return pointers

In C, functions can return pointers. This is a powerful feature, but is often abused, leading to bugs and memory leaks. The following are some things you need to pay attention to when using functions to return pointers:

• The pointer must point to a valid object

Points to an invalid object Pointers will cause undefined behavior. Before a function returns a pointer, make sure the object pointed to is valid.

• Do not modify the object pointed to by the pointer after the function returns

If the object pointed to by the pointer is modified after the function returns, other code uses the pointer You may get unexpected results.

• The caller is responsible for managing the memory

The pointer returned by the function points to the dynamically allocated memory on the heap. Unless it is explicitly released, otherwise the pointer Memory will be leaked. The caller is responsible for managing this memory and releasing it when it is no longer needed.

Practical case

The following is an example of a function returning a pointer:

int* GetArray() {
  int* array = new int[10];
  for (int i = 0; i < 10; ++i) {
    array[i] = i;
  }
  return array;
}

In this example, GetArray() The function returns a pointer to an array allocated on the heap. It is the caller's responsibility to free the array when it is no longer needed.

Use shared_ptr to manage memory

In order to avoid memory leaks, you can use shared_ptr smart pointers to manage pointers returned by functions. shared_ptr will automatically release the memory it points to, so that the caller does not need to manage it.

shared_ptr<int> GetArray() {
  shared_ptr<int> array(new int[10]);
  for (int i = 0; i < 10; ++i) {
    array[i] = i;
  }
  return array;
}

In the above example, GetArray() returns a shared_ptr that points to an array allocated on the heap. When shared_ptr is destroyed, it automatically releases the memory pointed to.

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