Bug memory management

C++11 Initializing new gameplay for members of

C++11 Supports initialization and assignment of non static member variables when declared ,== But note that this is not initialization , Here is the default value for the declared member variable .==

---

Understand encapsulation again

C++ It's an object-oriented program ,== Object oriented has three major features, namely ： encapsulation 、 Inherit 、 polymorphic ==.
C++ By class , Combine the properties and behavior of an object , Make it more consistent with people's cognition of a thing , Package everything that belongs to the object ; Selectively open some of its functions through access qualifiers to interact with other objects , For some implementation details inside the object , External users do not need to know , I see. It doesn't work in some cases , Instead, it increases the difficulty of use or maintenance , Complicate the whole thing .

---

Understand object orientation again

It can be seen that object-oriented is actually simulating the abstract mapping of the real world

---

C/C++ memory management

---

C/C++ Distribution of memory

Let's take a look at the following code and related problems

== Virtual process address space ==

【 explain 】

1. Stack Also called stack , Non static local variables / Function parameter / Return value and so on , The stack is growing down .
2. Memory mapped segments It's efficient I/O How to map , For loading a shared dynamic memory library . Users can use the system interface to create shared data
   Shared memory , Do interprocess communication .（Linux If you don't learn this in the course , Now just need to know ）
3. Pile up Dynamic memory allocation for program runtime , The heap can grow up .
4. Data segment – Store global and static data .
5. Code segment – Executable code / Read only constants .

---

C Dynamic memory management in language

==malloc/calloc/realloc and free==

【 Interview questions 】

malloc/calloc/realloc The difference between ？

---

C++ Memory management

C Language memory management is C++ You can continue to use , But there are some places that can't be helped, and it's troublesome to use , therefore C++ It also puts forward its own memory management mode ：== adopt new and delete Operator for dynamic memory management ==.

---

new/delete Operation built-in type

int main(){	//c Language application 10 individual int Array of 	int* pa = (int*)malloc(sizeof(int)*10);	//c++ apply 10 individual int Array of 	int* pb = new int[10];	//c Language free space 	free(pa);	//c++ Release space 	delete[] pb;	//c Language application 1 individual int	int* a = (int*)malloc(sizeof(int));	//c++ apply 1 individual int	int* b = new int;	//c Language free space 	free(a);	//c++ Release space 	delete b;	return 0;}

struct ListNode{	ListNode* _next;	ListNode* _prev;	int _val;	ListNode(int val = 0)		:_next(nullptr)		, _prev(nullptr)		,_val(val)	{		cout << "ListNode(int val = 0" << endl;	}	~ListNode()	{		cout << "ListNode()" << endl;	}};int main(){	//c Language to create linked list nodes 	struct ListNode* n1 = (struct ListNode*)malloc(sizeof(struct ListNode));	//free Is to free up space directly 	free(n1);	//c++ Create a linked list node 	ListNode* n2 = new ListNode(10);	//delete  It is to deconstruct and clean up before releasing space 	delete n2;	return 0;}

Be careful ： When applying for a custom type of space ,new Constructor will be called ,delete Will call the destructor , and malloc And free Can't .

struct ListNode{	ListNode* _next;	ListNode* _prev;	int _val;	ListNode(int val = 0)		:_next(nullptr)		, _prev(nullptr)		, _val(val)	{		cout << "ListNode(int val = 0" << endl;	}	~ListNode()	{		cout << "ListNode()" << endl;	}};int main(){	//c Language to create linked list nodes 	struct ListNode* n1 = (struct ListNode*)malloc(sizeof(struct ListNode));	//free Is to free up space directly 	free(n1);	//c++ Create a linked list node 	ListNode* n2 = new ListNode[10]{1,2,3,4,5,6,7,8,9,0};	//delete  It is to deconstruct and clean up before releasing space 	delete[] n2;	return 0;}