php new self()和new static()，phpnewselfstatic

The role and usage of static in C language: 1. Variable scope; 2. Life cycle; 3. Internal function; 4. Modify global variables; 5. Modify function; 6. Other uses; Detailed introduction: 1. Variable scope, when If there is the static keyword before a variable, then the scope of the variable is limited to the file in which it is declared. In other words, the variable is a "file-level scope", which is very useful for preventing the "duplicate definition" problem of variables; 2. Life cycle, static variables are initialized once when the program starts executing, and destroyed when the program ends, etc.

Practical application scenarios and usage skills of the static keyword in C language 1. Overview static is a keyword in C language, used to modify variables and functions. Its function is to change its life cycle and visibility during program running, making variables and functions static. This article will introduce the actual application scenarios and usage techniques of the static keyword, and illustrate it through specific code examples. 2. Static variables extend the life cycle of variables. Using the static keyword to modify local variables can extend their life cycle.

1. static Please look at the following program first: publicclassHello{publicstaticvoidmain(String[]args){//(1)System.out.println("Hello, world!");//(2)}} Have seen this Segment programs are familiar to most people who have studied Java. Even if you have not learned Java but have learned other high-level languages, such as C, you should be able to understand the meaning of this code. It simply outputs "Hello, world" and has no other use. However, it shows the main purpose of the static keyword.

Modifier abstract (abstract) 1. Abstract can modify a class (1) The class modified by abstract is called an abstract class (2) Syntax: abstractclass class name {} (3) Features: Abstract classes cannot create objects separately, but they can be declared Reference the abstract class name reference name; (4) Abstract classes can define member variables and member methods (5) Abstract classes have constructors. When used to create subclass objects, jvm creates a parent class object by default; abstract constructor methods apply Applied when jvm creates parent class object. 2. Abstract can modify methods (1) The method modified by asbtract is called an abstract method (2) Syntax: access modifier abstract return value

The functions of static: 1. Variables; 2. Methods; 3. Classes; 4. Other uses; 5. Multi-threaded environment; 6. Performance optimization; 7. Singleton mode; 8. Constants; 9. Local variables; 10. Memory Layout optimization; 11. Avoid repeated initialization; 12. Use in functions. Detailed introduction: 1. Variables, static variables. When a variable is declared as static, it belongs to the class level, not the instance level, which means that no matter how many objects are created, only one static variable exists, and all objects share this Static variables and so on.

Springboot reads the pro file and injects static static variables mailConfig.properties#Server mail.host=smtp.qq.com#Port number mail.port=587#Email account mail.userName=hzy_daybreak_lc@foxmail.com#Email authorization code mail.passWord =vxbkycyjkceocbdc#Time delay mail.timeout=25000#Sender mail.emailForm=hzy_daybreak_lc@foxmail.com#Sender mai

The "static" in php static static methods means that these properties and methods can be called directly without instantiating the class; static is a keyword used to modify the properties and methods of the class, and its usage syntax is such as "class Foo {public static $my_static = 'hello';}".

PHP is a popular open source server-side scripting language widely used in web development. The PHP language is not only easy to learn and use, but also supports a variety of programming paradigms, object-oriented programming, functional programming, etc. In PHP, there are some special syntax keywords, such as Static, Final, Abstract, etc. These keywords have special functions in object-oriented programming. This article will introduce these keywords in detail. Static keyword In PHP, the Static keyword has two uses