How to use php anonymous functions

Usage of php anonymous functions:

Considering memory factors, some functions that only need to be called once can be written in the form of anonymous functions, which can be cleared after use, as simple and efficient as post-it notes.

Characteristics of anonymous functions: 1. The function has no name and will only be used once.

2. Usually anonymous functions are assigned to a variable.

3. The calling method is also to use variables.

4. Can be deleted immediately after calling.

Result: hello!

Result: 10

Result: 13

This is my first blog post. From now on, I will write one every day to motivate myself to make progress~~