PHP basics-environment/variables/functions, etc.

• Chapter1 PHP environment and operating principles
• 1-1 Use phpStudy to create a php local development environment
• 1-2 Common plug-ins and configurations of VSCODE editor
• 1-3 PHP operating principle and composition of PHP program
• 1-4 How to print output of PHP running results
• Chapter2 Detailed explanation of php variables and constants
• 2-1 Naming methods and type characteristics of php variables
• 2-2 Value passing and reference passing of PHP variables
• 2-3 Detection and deletion of PHP variables
• 2-4 Detailed explanation of data types of PHP variables
• 2-5 Scope and access methods of PHP variables
• 2-6 Static variables and application scenarios in PHP
• 2-7 Detailed explanation of PHP variable filter (1)
• 2-8 Detailed explanation of PHP variable filter (2)
• 2-9 Detailed explanation of constants in PHP (1)
• 2-10 Detailed explanation of constants in PHP (2)
• Chapter3 Operators and flow control
• 3-1 PHP common operators (1)
• 3-2 PHP common operators (2)
• 3-3 PHP common operators (3)
• 3-4 Process control-branch structure (1)
• 3-5 Process control-branch structure (2)
• 3-6 Process control-loop structure
• Chapter4 Detailed explanation of functions in PHP
• 4-1 Function declaration and function type (1)
• 4-2 Function declaration and function type (2)
• 4-3 How to return multiple values ​​from a function (1)
• 4-4 How to return multiple values ​​from a function (2)
• 4-5 Explain in detail the parameters in the function (1)
• 4-6 Describe the parameters in functions in detail (2)
• 4-7 Explain in detail the parameters in the function (3)
• 4-8 Describe callback functions and applications in detail
• 4-9 Functions with namespaces
• Chapter5 Strings and string processing functions
• 5-1 Commonly used definition methods of strings (1)
• 5-2 Commonly used definition methods of strings (2)
• 5-3 Common string operation functions (1)
• 5-4 Common string operation functions (2)
• 5-5 Common string operation functions (3)
• 5-6 Common string operation functions (4)
• 5-7 Common string operation functions (5)
• 5-8 Common string operation functions (6)
• 5-9 Common string operation functions (7)
• 5-10 Common string operation functions (8)
• Chapter6 Arrays and array processing functions
• 6-1 Create a local PHP execution environment from the command line
• 6-2 Classification of PHP arrays
• 6-3 Definition and access of PHP arrays
• 6-4 PHP array traversal (1)
• 6-5 PHP array traversal (2)
• 6-6 PHP array common operation functions (1)
• 6-7 PHP array common operation functions (2)
• 6-8 PHP array common operation functions (3)
• 6-9 PHP array common operation functions (4)
• 6-10 PHP array common operation functions (5)
• 6-11 PHP array common operation functions (6)
• 6-12 PHP array common operation functions (7)
• 6-13 PHP array common operation functions (8)
• 6-14 PHP array common operation functions (9)
• Chapter7 How to load external files
• 7-1 Conditional loading of file loading (1)
• 7-2 Conditional loading of file loading (2)
• 7-3 Forced loading of file loading (1)
• 7-4 File loading forced loading