Php Data type and variable scope

Php Data type and variable scope 1) php supports the following basic data types:

Integer, Float, String, Boolean, Array, and Object. In addition, there are two special types: NULL or resource ).

Note: a variable that is not assigned a value, has been reset, or has been assigned a special value of NULL is a NULL variable.

A specific built-in function (such as a database function) will return a variable of the resource type.

2) scope refers to the range in which a variable can be used or visible in a script. PHP has six basic scope rules:

2.1) built-in Super global variables can be used and visible anywhere in the script;

2.2) constants, once declared, can be globally visible;

2.3) the global variables declared in a script are visible throughout the script;

2.4) when the variable used in the function is declared as a global variable, its name must be consistent with the global variable name;

2.5) variables created and declared as static within the function cannot be visible outside the function, but this value can be kept during multiple function executions;

2.6) the variable created in the function is local to the function. when the function is terminated, the variable does not exist.

Note: The Complete List of Super global variables is as follows:

$ GLOBALS ?? All global variable arrays;

$ _ SERVER ?? Array of server environment variables;

$ _ GET ?? The variable array passed to the script through the GET method;

$ _ POST ?? Array of variables passed to the script through the POST method;

$ _ COOKIE ?? Cookie variable array;

$ _ FILES ?? Array of variables related to file upload;

$ _ ENV ?? Environment variable array;

$ _ REQUEST ?? An array of all input variables, including $ _ GET, $ _ POST, and $ _ COOKIE;

$ _ SESSION ?? An array of session variables.

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