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There are three main data types in PHP:
1. Scalar data types
Scalar data types include the following. (Recommended learning: PHP video tutorial)
(1) boolean: Boolean type
Boolean variables are the simplest of PHP variables. It holds a True or False value. Where True or False is an internal keyword of PHP. To set a Boolean variable, just assign True or False to the variable
(2) string: String
A string is a continuous sequence of characters. Each character in the string characters occupy only one byte. In PHP, there are three ways to define strings:
single quote method,
double quote method,
Heredoc method.
(3) integer: integer
The integer data type can only contain integers. These data types can be positive or negative numbers. In 32-bit operating systems, the valid range is 2 147 483 648 ~ 2 147 483 647.
(4)double: floating point number
The floating point data type can be used to store numbers or decimals. The precision it provides is not much larger than integers. In 32-bit operating systems, the valid range is 1.7E-308 ~ 1.7E 308.
2. Composite data types
Compound data types include the following two types.
(1) array: Array
can be two-dimensional, three-dimensional or multi-dimensional. Each element in the array can be string, integer or double, or it can be an array.
(2) object: object type
3. Special data types
Special data types include the following two types.
(1) resource: Resource
Resources are special data types required by several functions in PHP and are allocated by programmers.
(2) null: Null value
Null value is the simplest data type. Indicates that no value is set for the variable. In addition, null values (NULL) are not case-sensitive.
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