PHP file reference with custom function

References between PHP files

• Include language structure
  • Format: mixed include (string resource); Load a resource file resource into the current PHP program;
    • When a resource resource is a resource on the Internet, the option Allow_url_include in profile php.ini needs to be set to ON (Allow_url_include = ON).
• Require language structure
  • Basically the same as include;
  • The difference: When using include, if an error occurs or the reference file is not found, continue to execute the following statement;
    When using require, the program runs if an error occurs or the reference file is not found.
• Include_once and require_once language structure
  • Format: Mixed include_once (string resource); Loading a resource file resource into the current PHP program, avoiding multiple references to the same PHP file and causing the function or variable to be duplicated;
    • Returns False if the resource file resource is not found and the file is first loaded, returns an integer of 1, found and loaded, returns TRUE.

Custom functions

function functionname ($param 1$param 2$param 3$paramn=  DefaultValue) {     function body        return value;}

Syntax format:

1. function: A keyword that defines a custom function;
2. functionname: function names for custom functions;
3. $param: Define the parameters of the function;
4. DefaultValue: The default value of the function parameter;
5. Function Body: function realization, function body is the statement block that executes when function is called;
6. Return: The execution of this function is immediately terminated when the program runs to return.

Parameter assignment methods for custom functions

• Transfer value Assignment
• Transfer Address Assignment value
  • Append a "&" character to the function's parameter name to implement the address assignment, for example:& $value;
  • When using this method, the value passed to the function cannot be a constant;

Global keyword

• Add the keyword Global (example: Global $value) before the defined variable name to change the local variable to a global variable;
  • Note: While using global to define global variables within a function, you cannot assign a value to the variable using an assignment statement.

Static keyword

• With the static keyword in front of the variable, you can keep the variables in the function body from this call until the next call;
  • Note: Static variables are only valid in the current execution of the PHP program, and refreshing the page will start all over again.

PHP file reference with custom function