PHP Data Types

Two Data Type Categories

1. Scalar - contains only one value at a time


2. Composite or Compound - array and objects

Four scalar types supported

1. boolean - a value that can only either be true or false


2. int - a signed numeric integer value


3. float - a signed floating-point value


4. string - a collection of binary data

Numeric Values

PHP recognizes two types of numbers

1. integers
   - the int data type is used to represent signed integers


2. floating-point values
   - also called float and sometimes double, are numbers that have a fractional component

Numeric Notations

1. Decimal - standard decimal notation.
   ex. 10; -11; 1452
   Note: no thousand separator is needed or allowed


2. Octal - identified by its leading zero (like the access permission of Unix)
   ex. 0666, 0100


3. Hexadecimal
   ex. 0x123, 0XFF; -0x100

Note
The leading 0x prefix are both case-insensitive
Note
Octal numbers can easily confused with decimal numbers and can lead to some consequences

Two supported notations for Floating-point numbers

1. Decimal - traditional decimal notation
   ex. 0.12; 1234.43; -.123


2. Exponential - composed of a mantissa value followed by a case-insensitive letter E then an exponent value.
   ex. 2E7, 1.2e2

Note

1. The precision and range of both types varies depending on the platform on which your scripts run
   ex. 64-bit platforms may be capable of representing a wider range of integer numbers than 32-bit platforms


2. PHP doesn't tract overflows


3. Float data type is not always capable of representing numbers in the way you expect it to.
   ex. echo (int)((0.1 + 0.7) * 10);
   this results to 7 instead of 8 since the result of this simple arithmetic expression is stored internally as 7.999999 instead of 8.0.

Strings

An ordered collection of binary data.

• could be text, content of an image file, spreadsheed or even a music recording.

Booleans

• can only contain either TRUE or FALSE.


• used as basis for logical operations.

Note
When converting data to and from the Boolean type, several rules apply:

1. When a numeric variable is converted to boolean data type, the value becomes false if the variable contains zero and true otherwise.


2. When a string variable is converted to boolean data type, the value becomes false only when the variable is empty or if it contains a single character 0. Other values, it is converted to true.


3. When a boolean variable is converted to a numeric or string, it becomes 1 if it is true, and 0 otherwise.