Using PHP
Portability: cross-platform development language.
Low cost: open-source development language, you can view its source code, free to use, modify, and publish again.
It supports multiple databases: MySQL PostgreSQL Oracle, MongoDB, MSSQL, SQLite.
Object-oriented support: abstract classes, interfaces, constructors, destructors.
PHP variables
Variable is a temporary space to store data. Such as: $ name = "fairy";
Variable naming rules:
This variable can contain: uppercase and lowercase letters, numbers, underscores.
php variable declaration is not required in advance, you can use direct assignment.
php variable can not start with a number; eg: $ 78jj = 900 // illegal variable name
Php variable names can be keyword; such as: $ true = 200;
Variable names are case sensitive
Variable names to be meaningful.
There are four kinds of unlikely php variable scope:
local global static parameter
php variable data types
PHP and JS, the type of a variable, depending on what the value of poetry.
Data type JS of:
(1) the basic data types: String, Boolean, Number, null, undefined
(2) complex data types: array, object, function
data type in PHP:
(1) the basic data type (4): int (integer), float (float), boolean (Boolean), string (character)
(2) complex data type (2): array (array), object (object)
(3) special data types ( 2): resource (resources), NULL (empty)
resource type: can be understood, the result of access to external files returned.
For example: PHP connect to the database, PHP create image files.
NULL type
NULL type: Only one value is NULL, no variable represents the assignment. The following cases on behalf of NULL.
$ G = NULL; // NULL value variable assignment
unset ($ g) // delete a variable
Only two Boolean values true and false.
Digital Type
Integer: refers to integer, 10, 200, -200, -23
Float: refers to the decimal point, 90,23.90 -90, 89
Character
1) single quotation marks, can only be used in single quotes \ ', \\
example: $ name =' Beijing ';
(2) double quotation marks, double quotes may be used in all the escape character.
For example: $ name = "Beijing";
(. 3) heredoc manner: long text can be saved
heredoc syntax as
$ STR = <<< the EOF
// write a lot of content can be intermediate
the EOF;