Classification of citations, four types of citations

1. Strong reference: Something like "object obj = new object()", no matter what, as long as a strong reference relationship exists, the garbage collector will never drop the referenced object.

2. Soft reference: Describe some objects that are still useful, but not necessary, objects that are only associated with soft references, and will throw these objects before the system is about to have an out-of-memory exception, and if there is not enough memory this time, an out-of-memory exception will be thrown. (for caching mechanisms).

3. Weak reference: is also a description of non-essential objects, weaker than soft references, and objects associated with weak references can only survive and rub until the next garbage collection occurs. When garbage collection starts working, objects associated with only weak references will be dropped, regardless of whether the current memory is sufficient.

It is suitable for storing metadata, such as classloader references. If no class is loaded, then there is no reference to the classloader.

Once the last strong reference is removed, the classloader with only the weak reference is **. ）

4. Phantom reference: Also known as a "ghost reference" or "phantom reference", it is the weakest type of referential relationship. Whether an object exists by a virtual reference does not affect its lifetime at all, and there is no way to obtain an instance of an object through a virtual reference.

The only purpose of setting a virtual reference to an object is to receive a system notification when the object is called. (Commonly used to manage direct memory, also known as off-heap memory).

The role of quotation is to make the argument conclusive, persuasive, inspiring, and concise, subtle and elegant.

1. Quotation can make the language expressed concise, vivid and lively, and add appeal.

2. Quotation is very helpful to explain the meaning of Zhaoli's expression, provide strong arguments for your own views and opinions, and enhance persuasiveness.

3. The role of quotation is to make the argument conclusive and sufficient, enhance the persuasiveness, be inspiring, and the language is concise, subtle and elegant.

1. Positive citation. Positive use is also known as "positive quotation", that is, the citation has a positive attitude towards the quoted sentence, and is used when the quotation is consistent with the original meaning. Positive quotation is generally used to confirm one's own views and express one's thoughts and feelings.

2. Reverse citation. Reverse use, also known as "reverse quotation", means that the quoter judges the quoted sentence and has a negative attitude, that is, the meaning used is the opposite of the original meaning, in order to achieve unconventionality or play a sarcastic role.

3. Borrowed by friends. There are two types of borrowing. One is also known as "reuse", that is, the original meaning of the original text and the meaning to be expressed are neither the same nor the opposite, but only related in a certain aspect.

It can bring forth the new, enhance the vividness, produce a humorous effect, and can also arouse the reader's association with the story and enhance the image.

The value types of c are: structs (numeric, bool, user-defined structs), enumerations, nullables.

c Reference types include: array, user-defined class, interface, delegate, object, string.

The elements of an array, whether they are reference or value, are stored on the managed heap.

A reference type stores a reference in the stack, and its actual storage location is on the managed heap. For convenience, this article refers to the reference type deployed on the hosted push.

A value type is always assigned where it is declared: when it is a field, it is stored following the variable (instance) to which it belongs; When used as a local variable, it is stored on the stack.

The value type has better efficiency in memory management and does not support polymorphism, which is suitable for use as a carrier for storing data; Reference types are polymorphic and are suitable for defining the behavior of your application.

I am a ——— who graduated from Shanghai Quanding Software College

The class defined is a reference type, but the others are not.

(reference type)

Reference is a new variable type in C++ and is an important complement to C. What it does is give the variable an alias. If you want to give an alias to a variable a, you can write it like this:

int a;int &b=a;

This shows that B is a "reference" of A, i.e. an alias for A. With such a statement, the use of a or b serves the same purpose, both representing the same variable. In the above reference, & is a "reference declarant" and does not represent an address.

Don't think of it as "assigning the value of a to the address of b". Data of reference types is stored in the in-memory heap, and in the memory unit only the addresses of the objects in the heap. Declaring a reference does not open up a memory unit, and both b and a represent the same variable unit.

Note: When you declare a reference variable type, you must also initialize it, i.e. declare which variable it represents. After you declare a reference to a variable, the reference is associated with the variable it represents for the duration of the function.

It can no longer be used as an alias for other variables. The following usage is incorrect:

int a1,a2;

int &b=a1;

int &b=a2;Trying to make B an alias (quote) for A2 will not work. This is wrong.

We can assign the value of a2 to b.

b=a2;